americano & vendor libraries updates

hi,

just a few updates that i'll do also for the cozy-template in coffee :
* updated the version of americano and cozy-americano so the server can start (the current version had problems with express)
* updated vendor libraries versions (jquery, underscore, backbone and bootstrap)
* updated config.coffee in client dir (removed path to normalize as it's coming with bootstrap, and helper.css that i couldn't find)

feel free to check and request other changes