Enable mobile view for website.

The documentation currently uses responsive Bootstrap, but didn't
include the correct meta tag for proper display on mobile devices.
Merge branch 'master' of https://github.com/dotcloud/docker
Merge branch 'master' of https://github.com/dotcloud/docker
Merge branch 'master' of https://github.com/dotcloud/docker
Merge pull request #1593 from kyleconroy/master

Enable mobile view for website.