Fix issues to make git-2.x working

- Changed the regexp to find the current branch to be compatible with
  git-2.0.0. It should be backward compatible with git-1.x
- Fixed option passing from the status menu to the diff method.

Git 2.0.0 drops the '#' in the output.

example:


> OSX 10.9 with git-2.0
$ git --version
  | git version 2.0.0
$ cd ~/playpen/xiki; git status
  | On branch git2-fixes
  | nothing to commit, working directory clean

> Ubuntu 12.04 with git 1.7
$ ssh derby git --version
  | git version 1.7.9.5
$ ssh derby 'cd src/bill; git status;'
  | # On branch rails
  | nothing to commit (working directory clean)


the other fix is for an error when asking the status. This is delegated to the diff method which takes a block as options, however no block is passed to the diff call.