StatefulBeanContext doesn't override equals()

Really a side issue to EJBTHREE-1367.

StatefulBeanContext does not override Object.equals(), so it relies on object identity. This breaks if the context has been serialized and deserialized (i.e. passivated/activated or replaced via replication from another node).

Side issue to EJBTHREE-1367 since the place where SBC.equals() matters is in the extra cache maintained by InfinitePool.activeList. This equals issue makes matters worse, since because of it if an SFSB has been serialized/deserialized, when it is removed the ref won't get cleared from the InfinitePool.activeList. The list will keep growing until the bean is undeployed.