Update PersistenceContextsImpl.java

I´m facing some problems using seam persistence(3.0.0.Final) in clustered tomcat6.
When using session replication throught DeltaManager, the following exception occurs:

org.apache.catalina.ha.session.DeltaManager requestCompleted
SEVERE: Unable to serialize delta request for sessionid [4F3785FD97924B5DD4D948B562F057E2.node2]
java.io.NotSerializableException: org.jboss.seam.persistence.PersistenceContextsImpl$PersistenceContextDefintition
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1164)

		
		
I´ve modified the inner class PersistenceContextDefintition removing static and implementing Serializable to solve my problem.
Merge pull request #14 from hernandazevedo/patch-1

Update PersistenceContextsImpl.java