Auto open issue for @deprecated

[m-kuhn]

It would be great to allow auto-opening issues for @deprecated notices in method headers to document api changes.

According to @mbernasocchi :

listen to https://developer.github.com/v3/activity/events/types/#pushevent
from the payload:
url = payload["commits"]["head_commit"]["url"]
diff_url = url + '.diff'
grep deprecated in diff_url content

Maybe we can even add a small tag language where we can specify further information in the commit message for relevant changelog information.

[m-kuhn]

Something like here maybe
https://github.com/ELLIOTTCABLE/.gitlabels