updated tomcat versions && fixed some tests

fixed tests:
testFormAuthDontCauseSessionStaleness(de.javakaffee.web.msm.integration.NonStickySessionsIntegrationTC7Test)
testIgnoredResourcesWithFormAuthDontCauseSessionStaleness(de.javakaffee.web.msm.integration.NonStickySessionsIntegrationTC7Test)
testSerializationOfAuthStuffWithFormAuth(de.javakaffee.web.msm.integration.TomcatFailoverIntegrationTC7Test)