Replacing local interfaces with remote ones and move them to the shared jar due to errors after adding frontoffice and mobilegateway.

Lookup for EJBs via JNDI (use LookupManager for that).
Rename bean in backoffice-web to BackOfficeBean as it makes more sense.
Move webservice annotations to mobilegateway-web.
Fix pom.xml and persistence.xml after Kamil's commit. Replace UserManagerLocal with UserManagerRemote.