[mediacapture-image] new commits pushed by alvestrand

The following commits were just pushed by alvestrand to https://github.com/w3c/mediacapture-image:

* Change mailinglist to public-webrtc

The mailing list "public-media-capture" is not active anymore and has
been effectively replaced by public-webrtc. This change updates the
information on the spec.
  by Armando Miraglia
https://github.com/w3c/mediacapture-image/commit/91fa247b699c10894475fa3cafdd0eb7b3579e6b

* Merge pull request #207 from armax00/master

Change mailing-list to public-webrtc
  by Harald Alvestrand
https://github.com/w3c/mediacapture-image/commit/a260906f9cb1362a46f6eabbc7981538b46acf26