Rename "status" variable in _lp_battery function

"status" is a reserved word in ZSH (depending the current configuration).
With this commit, we don't depend anymore on this settings.
git: fix git directory detection

Typo in git rev-parse argument
CHANGES: log _lp_git_branch fix
Add 'sudo' feature (#335)

Change the color of the prompt mark while 'sudo' credentials are cached.

New variables:
- LP_ENABLE_SUDO
- LP_COLOR_MARK_SUDO

https://github.com/nojhan/liquidprompt/issues/335
CHANGES: add 'sudo' feature
Merge branch 'feature/sudo' into develop

Closes #335