Skip fedmsg.meta tests if underspecified.

We used to just mark them as 'passing' which was a little disingenuous.
Add stubs for fedmsg.meta.msg2{emails,avatars}
s/gravatar/avatar/g
Use fedmsg.meta.msg2avatars, removing the need for python-fedora.
Fix a typo caught by puiterwijk
Merge pull request #136 from fedora-infra/feature/python-fedora-removal

Feature/python fedora removal