Customize information formats with args

[ahaasler]

This allows to customize formats for tag, behind, ahead, staged, unmerged, changed, untracked and stash in a config file:

"gitstatus": {
    "args": {
        "tag_format": " {}",
        "behind_format": " {}",
        "ahead_format": " {}",
        "staged_format": " {}",
        "unmerged_format": " {}",
        "changed_format": " {}",
        "untracked_format": " {}",
        "stashed_format": " {}"
    }
}

Users may want to change an icon, remove the specific number of unmerged files and just want to know there's unmerged content, or hide untracked files.

[cowboy]

Is there any reason why this can't be merged? Thanks!

[jaspernbrouwer]

No, I'm afraid I don't have a good reason, it boils down to lack of time 😞

It does look interesting though, so I'll try to push this up my priority list!

[jcharaoui]

I finally came around to testing this PR and it works great.

I prefer this solution to other that have been proposed since then, as it seems to be the most flexible.

[ahaasler]

It's great to see this merged!