Powerline-gitstatus

* New `format` argument allowing to customisation of the segment symbols
* New `last`, `annotated`, `contains` and `exact` options for `show_tag` argument. The behavior when `show_tag` is `True` changed from `last` to `exact`
* New `detached_head_style` argument
* Bypass the user-defined locale, fixes detached HEAD display when user has non-English locale

Introduced the `show_tag` argument, which shows the most recent tag reachable in the current branch.

Introduced the `use_dash_c` argument.

When `true` (the default), we will call `git` with the `-C` argument, but that requires git 1.8.5 or higher.

When that requirement cannot be met, one can pass `false`, which will fall back to the `--git-dir` and `--work-tree` arguments. Because we need to traverse the current working directory up to root and search for a `.git` directory, this options is less performant and accurate. Therefor using git 1.8.5 or higher is recommended.

This release should solve the working directory issues (1 and 4) once and for all!

Fixed issue 4, where segment won't show when in a sub-directory of a working copy.

Fixed issue 1, where segment won't show when using the `powerline-daemon`.