bloom should support the insertion of Changlog information into binaries

Now that the Changelog REP is getting finalized, bloom should support parsing and inserting changelog information into the binaries (debs, rpms, etc...).


There are three common cases bloom has to support:

- Releasing a package without a changelog
- Releasing a package with a changelog, but no previous changelog history
- Releasing a package with a changelog and a changelog history
- Releasing a package with the same upstream version a second time (no upstream changes)

Some other potential corner cases:

- Releasing a package with differing changelog history (different versions +/- in history)
- Releasing a package without a changelog, but a changelog history

There is some discussion on how to install the changelog file into the resulting debian as well:

https://groups.google.com/forum/?fromgroups=#!topic/ros-sig-buildsystem/vhI4YXZHl4Q