Flowplayer styles improved to work better with aspect ratios different from the default.

Based on: http://alistapart.com/article/creating-intrinsic-ratios-for-video
Update CHANGELOG and bower.json.
Add base play button styles.
Add 4:3 aspect ratio styles.
Update changelog.
Merge pull request #32 from incuna/improve-flowplayer-styles

Flowplayer styles improved to work better with aspect ratios different from the default.