upgrade to undertow 1.0.0.Alpha5
Fix client CERT test for the first time in two years
Initial clustering support
re-enable clustring tests

re-enable more tests

Fix configurations to use undertow
Don't get the servlet context till after the deployment is started
AS7-6797 AS7-6796 AS7-6798 Ignore tests for which we don't have Undertow support yet

 * AS7-6798 - disable mod cluster tests until we have proper undertow support
 * AS7-6811 - ignore tests
 * Minor clean up within tests and diable WebSecurityJBossWebXmlSecurityRolesTestCase as behaviour being tested currently considered invalid.
Small test modification to allow for authentication mechanism configured for web app to be returned after programatic authentication.
Changes after code review