Fix edge case of resolutions not working properly when resolving to branches.

There was still an edge case where a branch/tag was named with a valid semver.  The resolution would fail because the semver branch only checked the version from the bower.json.  In my particular case there is a repo with no bower.json (I have a PR in to add :-) ), but I think this behavior is consistent with other Bower behavior WRT semver in branches/tags.

Modifies bower/bower#819
Closes bower/bower#818