OAuth2 cookie parser

A new utilites class for parsing the new facebook OAuth2 cookie

Parses cookies beginning with "fbsr_" 
Adapted from http://stackoverflow.com/a/7551293/513564

Usage:

```
String accessToken = null;
		Map<String,String> fbCookie = FacebookOAuth2CookieParser.parseFacebookCookie(request.getCookies(), Constants.FACEBOOK_APP_ID, Constants.FACEBOOK_APP_SECRET);
	 	if(fbCookie!=null && fbCookie.containsKey("code")){
	 		String authorizationCode = fbCookie.get("code");
	 		AccessGrant accessGrant = oAuth2Template.exchangeForAccess(URLEncoder.encode(authorizationCode,"UTF-8"), "", null);
		 	if(accessGrant!=null){
		 		accessToken = accessGrant.getAccessToken();	
		 	}
	 	}
	 	return accessToken;
```