added a note about Symfony version in the HTTP fragment doc
added a note about Symfony version in the HTTP fragment doc

Xephi/Silex,naderman/Silex,naderman/Silex,jdreesen/Silex,GromNaN/Silex,Incognito/silex-fork,fabpot/Silex,arduanov/Silex,RayRutjes/Silex,gencer/Silex,mmauri04/Silex,akucherevskiy/developex_test,mTorres/Silex,RayRutjes/Silex,plotek/Silex,SpacePossum/Silex,mmauri04/Silex,beealone/Silex,plotek/Silex,SanderKnape/Silex,tcx1000/Silex,arduanov/Silex,cesarmarinhorj/Silex,CarsonF/Silex,naderman/Silex,GromNaN/Silex,romainneutron/Silex,jdreesen/Silex,fhinkel/Silex,mathroc/Silex,lokhman/Silex,cesarmarinhorj/Silex,cgsmith/Silex,SpacePossum/Silex,CarsonF/Silex,JPry/Silex,akucherevskiy/developex_test,beealone/Silex,lokhman/Silex,Incognito/silex-fork,silexphp/Silex,romainneutron/Silex,mTorres/Silex,tcx1000/Silex,akucherevskiy/developex_test,CarsonF/Silex,GromNaN/Silex,fabpot/Silex,Xephi/Silex,romainneutron/Silex,JPry/Silex,cgsmith/Silex,SanderKnape/Silex,mathroc/Silex,fhinkel/Silex