Adding JPA-Audit PU

Audit JPA unit is missing.  Deployment of ``auth-server.war`` causes:

```

Caused by: javax.persistence.PersistenceException: No Persistence provider for EntityManager named jpa-keycloak-audit-store
	at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:69) [hibernate-jpa-2.0-api-1.0.1.Final.jar:1.0.1.Final]
	at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47) [hibernate-jpa-2.0-api-1.0.1.Final.jar:1.0.1.Final]
	at org.keycloak.audit.jpa.JpaAuditProviderFactory.init(JpaAuditProviderFactory.java:24) [keycloak-audit-jpa-1.0-beta-1-SNAPSHOT.jar:]
	at org.keycloak.provider.ProviderFactoryLoader$LazyProviderFactory.create(ProviderFactoryLoader.java:73) [keycloak-core-1.0-beta-1-SNAPSHOT.jar:]
	at org.keycloak.services.DefaultProviderSession.getProvider(DefaultProviderSession.java:32) [keycloak-services-1.0-beta-1-SNAPSHOT.jar:]
	at org.keycloak.services.DefaultProviderSession.getProvider(DefaultProviderSession.java:23) [keycloak-services-1.0-beta-1-SNAPSHOT.jar:]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_09]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_09]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_09]
	at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_09]
	at org.jboss.resteasy.core.ContextParameterInjector$GenericDelegatingProxy.invoke(ContextParameterInjector.java:55) [resteasy-jaxrs-3.0.6.Final.jar:]
	at $Proxy148.getProvider(Unknown Source)	at org.keycloak.services.resources.RealmsResource.createAudit(RealmsResource.java:115) [keycloak-services-1.0-beta-1-SNAPSHOT.jar:]
	at org.keycloak.services.resources.RealmsResource.getTokenService(RealmsResource.java:71) [keycloak-services-1.0-beta-1-SNAPSHOT.jar:]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_09]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_09]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_09]
	at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_09]
	at org.jboss.resteasy.core.ResourceLocatorInvoker.createResource(ResourceLocatorInvoker.java:81) [resteasy-jaxrs-3.0.6.Final.jar:]
	at org.jboss.resteasy.core.ResourceLocatorInvoker.createResource(ResourceLocatorInvoker.java:60) [resteasy-jaxrs-3.0.6.Final.jar:]
	at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:102) [resteasy-jaxrs-3.0.6.Final.jar:]
	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356) [resteasy-jaxrs-3.0.6.Final.jar:]


```