Allow topic and otherwise comparisons to use "endswith".

This will be convenient especially for topics.  Instead of having
to define:

    trigger:
        topic: org.fedoraproject.stg.bodhi.update.request.testing

In one badge, and then *redefine* in another:

    trigger:
        topic: org.fedoraproject.prod.bodhi.update.request.testing

With this we can just define one badge rule with:

    trigger:
        topic: bodhi.update.request.testing