Fix dependencies on EJB3.1 API

The WAS 7 & WAS 8 remote container adapters depend on org.jboss.ejb3:jboss-ejb3-api that I cannot find neither in the official Maven repository nor in repository.jboss.org.
But I can build and use the WAS 8 adapter if I replace that dependency with org.jboss.spec.javax.ejb:jboss-ejb-api_3.1_spec.