Update remote tips on push
Merge pull request #1250 from jamill/push_update_tips

Update remote tips on push
Leak cleanup in push tests
Added git_branch_name().

This is a convenince function to get the branch name of a given ref.
The returned branch name is compatible with the name that can be
supplied e.g. to git_branch_lookup(). That is, the prefixes
"refs/heads" or "refs/remotes" is omitted.
Added test for git_branch_name().