`contributing.md`: Fix link
Merge pull request #180 from arthurvr/patch-1

`contributing.md`: Fix link
Fixed the code changes tracker RSS URL

The URL was changed a while ago.
Merge pull request #184 from phistuck/patch-1

Fixed the code changes tracker RSS URL
Merge pull request #182 from heatheramahan/master

Updates to Device Mode article
device-mode. update to new gfycats

cc #182
Update device-mode.html

Cleaned up some html tags to try and fix duplicate contents.
Fixed id for Simulate device orientation h3 tag.
Fixed non-breaking hyphen HTML Entity.
Added controls to videos.
Removed some limitations. Added Esc key tip.