Improve constraints of fat composer.json
Improve constraints of fat composer.json

* Change symfony/* from 2.1.* => ~2.1
* Delegate twig and monolog version selection to bridges

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