Merge ~sbeattie/usn-tool:usn_allbinary_source into usn-tool:master

[Steve Beattie]

usn.py: add --all-binary-source option

This adds the --all-binary-source option for the allbinaries section of
a USN, letting us link the source package with the binary packages
reference. This helps us retain this link, especially in USNs where
mutliple source packages are included; specifically kernel USNs are
problematic.

Additionally, in kernel USNs we drop linux-meta and linux-signed source
records to keep kernel USNs from exploding, but adding this option lets
us retain the connection and pass it on to the USN website for linking
and consumption by tools; it will help address
https://github.com/canonical/ubuntu-advantage-client/issues/1465

(At the moment, this change is a work-in-progress, but I need the merge request to reference elsewhere, though this is the first step that needs to land.)

diff --git a/usn.py b/usn.py
index b7dbf9d..4d106fd 100755
--- a/usn.py
+++ b/usn.py
@@ -163,6 +163,11 @@ def parse_options(argv):
                           Var("package"), "version"),
                     help="Set all binary package version with fix on the "
                          "given release")
+    register_option("--all-binary-source", metavar="SRC",
+                    path=("releases", Var("release"), "allbinaries",
+                          Var("package"), "source"),
+                    help="Set all binary package version with fix on the "
+                         "given release")
     register_option("--source-version", metavar="VER",
                     path=("releases", Var("release"), "sources",
                           Var("package"), "version"),