Update README.md
Merge remote-tracking branch 'theodo/master'

Conflicts:
	README.md
[sf2.3.x] Change flash message rendering
[sf2.3.x] Update DataTransformer calls
[sf2.3.x] Change Types default option setting
[sf2.3.x] Update form related changed function calls (WIP)
[sf2.3.x] Fix Layout actions
Dependecies bump for sf2.3
Make tests pass with Symfony 2.3
Build for Symfony 2.2 and 2.3
Loosen require on doctrine bundle
Merge remote-tracking branch 'upstream/sf2.3.x'

Conflicts:
	composer.json
Change class inheritance for backwards compatiblity
Check if ESI enabled in snippet renderer
Drop symfony 2.1 support
Merge pull request #77 from marekkalnik/master

Symfony 2.3 compatiblity