Validate if CDI 1.1 and Servlet 3

As suggested by Paulo Silveira here: https://groups.google.com/forum/#!topic/caelum-vraptor/QkgGx5ceh50, was added a validation for CDI 1.1 and Servlet 3. I wont validate for servlet 3.1 (Java EE 7) because VRaptor can run in Tomcat 7 + CDI 1.1 jars without problems.

And some validations were extracted to methods to get code more clear.

Servlet-api needs to be upgraded, since now we are working with servlets 3.1.