Myfaces should be able to gracefully handle a runtime with the bean validation API on the classpath but no impl

MyFaces does not tolerate well having the bean validation API on the classpath when there is no JSR 303 impl in place. As it stands currently, we will fail rendering any page that includes validation, whether or not it includes JSR 303 validation. We should fail more gracefully with a warning during the first attempt at initialization by the static method in org.apache.myfaces.ExternalSpecifications.

There is already some code commented out which essentially does this check. It appears it was only commented out due to the validation api not being on the myfaces impl classpath. I'll use this bug to uncomment that code and to update the pom to include a dependency on the bean validation api as in the myfaces api.