Cache-Control Feature

* Added ability to set Cache-Control headers
* Moved cache-control header settings into controller
* Removed extraneous "use" statement
* Updated test to pass empty array for cacheConfig
Move Cache-Control logic to a Util class + Add tests
Prevent XSS in JSONP callback

Replaces #103

See: http://stackoverflow.com/questions/2777021/do-i-need-to-sanitize-the-callback-parameter-from-a-jsonp-call
Fix: be less restrictive on callback validation
Fix branch-alias
Add CallbackValidator in order to improve the JSONP callback validation
Merge pull request #104 from FriendsOfSymfony/callback-validator

Callback validator
Test against PHP 5.5
Use JsonCallbackValidator lib
Merge pull request #107 from FriendsOfSymfony/use-jsonp-callback-validator

Use JsonCallbackValidator lib