Refactored ComposerGenerator with unit tests

I've updated travis-support to better handle the new branches we've created for framework/cms/installer.

Now you can use CORE_RELEASE=3 to target the feature branch for 3 (aliased as 3.2).

Also added are UNIT TESTS. That's right... tests for the testing addon.

I've pushed up a version to my local '3' branch of sapphire and ran this module to demonstrate that it works.

https://travis-ci.org/tractorcow/sapphire/jobs/43062248