Echo a character that represents whether the current repo is ahead, behind or has diverged from its upstream.
##### Default values:
+ ahead: `+`
+ behind: `-`
+ diverged: `±`
+ none: ` `
#### `git_is_repo`
Set `$status` to `0` if the current working directory belongs to a git repo.
#### `git_branch_name`
Echo the currently checked out branch name of the current repo.
#### `git_is_dirty`
Set `$status` to `0` if there are any changes to files already being tracked in the repo.
#### `git_is_staged`
Set `$status` to `0` if there [staged](http://programmers.stackexchange.com/questions/119782/what-does-stage-mean-in-git) changes.
#### `git_is_stashed`
Set `$status` to `0` if there are items in the [stash](https://git-scm.com/book/en/v1/Git-Tools-Stashing).
#### `git_is_touched`
Set `$status` to `0` if the repo has any changes whatsoever, including [tracked or untracked](http://stackoverflow.com/questions/9663507/what-is-tracked-files-and-untracked-files-in-the-context-of-git) files.