ASSERTION_SESSION_ATTRIBUTE_NAME for SAML2AuthenticationHandler should support an encrypted assertion

SAML2AuthenticationHandler is configured as follows in SP:

		<Handler class="org.picketlink.identity.federation.web.handlers.saml2.SAML2AuthenticationHandler">
			<Option Key="ASSERTION_SESSION_ATTRIBUTE_NAME" Value="samlResponse"/>
		</Handler>

If an assertion is NOT encrypted in IDP, it is stored in a session, but if encrypted, it is not stored in a session. Need support for encrypted assertion.