Add a gitstatus theme.

## GitStatus

![GitStatus](https://github.com/godfat/fish_prompt-gitstatus/raw/master/gitstatus.png)

#### Characteristics

* Displays host information in the command prompt when connected via ssh.

* Displays git information in the command prompt when inside a git repository.

  - Shows current branch name.
  - Shows * if working copy is dirty.
  - Shows # if everything is staged.
  - Shows no indicators if the working copy is clean.