Add function to get branch name

[JaroslawSlabik]

Hello,
Would it be a good idea to add a function that returns the name of the branch?
This function would be called GitGutterGetBranchName().

What do you think about this idea?

[airblade]

The aim of the plugin is to ease working with diffs and hunks. Showing the branch name is out of scope.

I assume this is for your status line. If you use a status line plugin, it probably already supports this; if you construct your own status line, adding the branch name would be straightforward.