git prune-branches

@kevgo please review

+ Changed a couple git helpers to take in parameters instead of operating on the current branch
+ Set the default branch on the remote repo to main (needed as the git prune-branches feature specs were deleting the master branch (since its not main) and you cannot delete the HEAD branch on the remote repo.
This will never kill any branch that is ahead of master. If you push up a branch that is behind or even with master, what side effects does deleting it really have? You will need to push it up again, but you won't lose any work