Resolve org.eclipse.jgit.lib.ObjectIdRef

Required for merging the first advertised ref at the end of git-clone-full.
The advertised refs of a FetchResult are of type ObjectIdRef.
Merge pull request #12 from stijnopheide/resolve-refs

Resolve org.eclipse.jgit.lib.ObjectIdRef
commit typo
Merge branch 'master' of github.com:clj-jgit/clj-jgit
Trying to make tests run on Travis-CI
Adding docstring
updated docs
Adding some docstrings
regenerated docs