Merge pull request #746 from mposolda/master

KEYCLOAK-738 Possible NPE in MemUserSessionProvider.getUserSessions
saml backchannel logout
merge
Merge pull request #747 from patriot1burke/master

saml backchannel logout
undertow slash redirect problem
Merge pull request #749 from patriot1burke/master

undertow slash redirect problem
KEYCLOAK-742 Added always-refresh-token option to adapters
KEYCLOAK-743 Stateless session mgmt. Drop statistics for adapters.
KEYCLOAK-741 Failure to refresh token should invalidate http session
Reduce logging
Merge pull request #750 from mposolda/stateless-session-mgmt

Stateless session mgmt
Fix mongo to pass with testsuite
Merge pull request #751 from mposolda/stateless-session-mgmt

Fix mongo to pass with testsuite
Test for KEYCLOAK-741
Merge pull request #752 from mposolda/stateless-session-mgmt

Test for KEYCLOAK-741