Update CONTRIBUTING.md

Add a note about pull requests to be done against dev branch
Update CONTRIBUTING.md
Initial rtl detection
Misuse of jquery object - use DOM object instead
Add initial rtl styles

We swap out images for the flipped versions, and modify any css
styles with hard-coded handedness.
Some playful rtl style fixes
Support RTL for sliders.

(Requires some additional data in javascript.)
Ensure LTR text for help menu (no translations yet anyway)
With preload=none the flash engine no longer preloads the video. (#305)
Add handler for hiding the error messages while navigating away

Fixes #272
Merge pull request #315 from chowey/i18n

Add RTL support - fixes #310
Merge pull request #324 from flowplayer/bug/272

Add handler for hiding the error messages while navigating away
Merge pull request #323 from flowplayer/bug/305

With preload=none the flash engine no longer preloads the video. (#305)
Changed to not start sending progress events before playback actually starts. Now the "is-poster" class is removed when the first progress event is received. (#182)
Merge pull request #327 from flowplayer/bug/182-2

A different approach to fixing #182
Only remove owned video-tags, closes #241
Add CHANGELOG.md
Use img tag to convert relative url to absolute fixes #148

(also don't use Array.forEach because it's unexistent in IE < 9)
Merge pull request #333 from flowplayer/bug/148

Use img tag to convert relative url to absolute fixes #148
Add note about #148 to changelog