Update README.md
Create basic security doc
Fix routing extension
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
Merge remote-tracking branch 'upstream/sf2.3.x'

Conflicts:
	composer.json
Change class inheritance for backwards compatiblity