Katello engine: request commits prepended with "Engine:"

Joseph, Tom, Eric,

As we work towards making katello an engine, I'd propose that we prepend
all commits that go in to the katello 'engine' branch with "Engine: ".
For example,
Engine: Initial work to allow Katello to be loaded as a Rails engine

This was done for the above commit, but I think we should all do the
same as we add in changes. This will allow us to more easily identify
changes related to the enginification.