Change 'policy-core' to support app persistence

Change 'policy-core' to support app persistence

This includes the following:

1) A new hook method 'newPolicySession(PolicySession)' that is called after
   the session has been created and initialized

2) Support for "adjunct" objects in 'PolicySession'

3) Added 'try/catch' blocks around feature method invocations

4) Added 'default' methods to interface 'PolicySessionFeatureAPI'

5) Removed 'PolicySessionFeatureAPI.isPersistenceEnabled()'

Conflicts:

	policy-core/src/main/java/org/openecomp/policy/drools/core/PolicySessionFeatureAPI.java

Change-Id: Ibc6d9eeacb6118d617e6c5ac53f6cef4c6ee1417
Signed-off-by: Ralph Straubs <rs8887@att.com>