Code review comment for lp:~andrea.corbellini/launchpad/blueprint-comments-part2

= Summary =

Bug #49698 is about giving the ability to comment on specifications.

== Proposed fix ==

This branch contains the interfaces and model changes needed.
Database schema changes can be found in
lp:~andrea-bs/launchpad/blueprint-comments-part1.

I've added two new interfaces: ISpecificationMessage and
ISpecificationMessageSet, following the bug comments' code.

== Pre-implementation notes ==

I discussed this part of the bug fix with intellectronica. He told me which
packages I had to modify and which classes I needed to write.

== Implementation details ==

lib/lp/blueprints/interfaces/specificationmessage.py:
 * Add ISpecificationMessage that represents a blueprint comment.
 * Add ISpecificationMessageSet, a set of all blueprint comments.

lib/lp/blueprints/model/specificationmessage.py:
 * Implement ISpecificationMessage and ISpecificationMessageSet.

lib/lp/blueprints/configure.zcml:
 * Add the configuration for the two new interfaces.

lib/lp/blueprints/doc/specificationmessage.txt:
 * Test comment creation and retrieval.

== Tests ==

bin/test -vv -t specificationmessage

== Demo and Q/A ==

There isn't a UI yet, so the only way to try the changes is using the doc
test.

= Launchpad lint =

Checking for conflicts. and issues in doctests and templates.
Running jslint, xmllint, pyflakes, and pylint.
Using normal rules.

Linting changed files:
  lib/lp/blueprints/configure.zcml
  lib/lp/blueprints/doc/specificationmessage.txt
  lib/lp/blueprints/interfaces/specificationmessage.py
  lib/lp/blueprints/model/specificationmessage.py