Handle not-quite-semver tags like "1.0"

Currently cannot fetch tag `1.0` because it is a valid range, but it is not a valid semver itself.

E.g.

    bower install cowboy/jquery-throttle-debounce#v1.0
    
    bower jquery-throttle-debounce#v1.0       not-cached git://github.com/cowboy/jquery-throttle-debounce.git#v1.0
    bower jquery-throttle-debounce#v1.0          resolve git://github.com/cowboy/jquery-throttle-debounce.git#v1.0
    bower jquery-throttle-debounce#v1.0     ENORESTARGET No tag found that was able to satisfy v1.0