bump grunt-css-flip to ~0.2.2

BS3 commits: 348e7a011a624bc48983be337c9f5fd723318aaf
Fixed navbar radius of example at docs

BS3 commits: bae289d1fe59d1c403b1a4fceaea6379f6008a2a
Improve accessibility of close buttons in modals & alerts

BS3 commits: 949b81f51171550bcec0d92e771793999e69a389
include RTL CSS CDN URL in Download docs

BS3 commits: d6104b11511a69fb48d1e438141f135a14c04122
document 13390

BS3 commits: 588889cdc5908279c59ca418da3ad4f4e8dd235a
Officially support Android Firefox

BS3 commits: 3bc95979a9318258e027830b35c840704eb1e3be
Wall of browser bugs: formatting tweaks

BS3 commits: fcbdbee9955ddcce76452b59aaee76b03005c507
add RTL CSS files to "What's included" section of docs

BS3 commits: 04028cf6feb62471a3788cd15804e62b9ce890d7