Support snap interface plugs and slots

Is this only an action that makes sense when the app is installed or at any time? My guess is we should have a "connections" panel of some sort that allows these to be toggled at a later date and perhaps an Android style "this app is requesting these permissions" dialog when installing (with the option of disabling them at that point).

Prior art in the phone - the modifiy existing permissions is in the system settings.

Added to Trello: https://trello.com/c/ZwWopznl/18-bug-1597314-support-for-apps-which-do-not-automatically-connect-to-slots

Sorry, imported in to the wrong place.

Added to Trello: https://trello.com/c/SE7C41X9/60-bug-1597314-support-for-apps-which-do-not-automatically-connect-to-slots

Opened a forum topic about the best way to implement this:
https://forum.snapcraft.io/t/connecting-plugs-and-slots-in-a-gui/776

Current plan:
- snap plugin will tell G-S to add a "Configure" button (or similar name) for each installed snap beside the remove button.
- When clicked, this will get the snap plugin to launch an interface editor program (can't be included in the plugin because plugins don't do UI; can't be in GNOME Software core because functionality is not shared between plugins).

GNOME Software upstream design is likely to end up with some "permissions" data being shown in GNOME Software, but being controlled from Control Centre. We can probably hook into the permissions code if it is appropriate.

This bug was fixed in the package gnome-software - 3.27.92-0ubuntu1

---------------
gnome-software (3.27.92-0ubuntu1) bionic; urgency=medium

  * New upstream release
  * debian/patches/0001-Don-t-use-app-ID-as-a-tie-break-when-ordering-search.patch
  * debian/patches/0001-Make-app-name-sorting-case-insensitive.patch
  * debian/patches/0001-Revert-snap-Show-revision-number-in-version-field.patch
  * debian/patches/0001-snap-Refactor-how-metadata-is-merged-between-install.patch
    - Applied upstream
  * debian/patches/0009-Display-a-warning-for-non-sandboxed-snaps.patch:
    - Update warning text
  * debian/patches/0012-Don-t-use-colour-to-differentiate-between-free-and-p.patch
    - Don't use red to indicate propietary software (LP: #1750533)
  * debian/patches/0013-overview-page-Rotate-featured-apps.patch:
    - Support showing multiple banners (LP: #1750548)
  * debian/patches/0014-Add-a-basic-permissions-system.patch:
    - Add basic system for connecting/disconnecting snap interfaces
      (LP: #1597314)

 -- Robert Ancell <email address hidden> Tue, 06 Mar 2018 16:46:42 +0100

Hello Will, or anyone else affected,

Accepted gnome-software into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gnome-software/3.20.5-0ubuntu0.16.04.11 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

I'm blocking this SRU for the moment because it introduces a regression and the banner of the featured app only shows the background image without any text.

@robert, could you please have a look?

I cannot reproduce the error from my previous comment anymore.

SRU verification for Xenial:

I have reproduced the problem with gnome-software 3.20.5-0ubuntu0.16.04.10 in xenial-updates and have verified that the version of gnome-software 3.20.5-0ubuntu0.16.04.11 in -proposed fixes the issue.

Marking as verification-done

This bug was fixed in the package gnome-software - 3.20.5-0ubuntu0.16.04.11

---------------
gnome-software (3.20.5-0ubuntu0.16.04.11) xenial; urgency=medium

  * debian/patches/0019-Support-channels.patch:
    - Make snap channel selection list scrollable (LP: #1768779)
  * debian/patches/0020-Add-a-basic-permission-system.patch
  * debian/patches/0021-Add-a-Snap-plugin.patch
    - Correctly handle snap install/remove failures (LP: #1762427)
    - Fix snaps without icons not showing (LP: #1763736)
    - Add basic system for connecting/disconnecting snap interfaces
      (LP: #1597314)
    - Alphabetically sort channel branch names (LP: #1769556)
  * debian/patches/0050-snap-Support-channels.patch:
    - Fix incorrect default install version being shown (LP: #1767445)

 -- Robert Ancell <email address hidden> Tue, 08 May 2018 12:02:36 +1200

The verification of the Stable Release Update for gnome-software has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.