Cleanup: “core” should be compatible with tomcat8, tomcat7 and tomcat6. We use Tomcat 7 version in “core” to match the new artifact naming in maven repositories.
5 tests are still failing in tomcat8 branch, many of them are caused by an invalid app initialisation under Tomcat8.
Temporary workaround: tomcat8 redirects form-auth to "//login"" instead of "/login”.

1 test is still failing:

```
  testSessionCreatedForContainerProtectedResourceIsStoredInMemcached(de.javakaffee.web.msm.integration.NonStickySessionsIntegrationTC8Test): id=CD88FE36E020759087DAB47489892C21-n1 expected:<302> but was:<200>
```
Better message exception

```
java.lang.AssertionError: IllegalState: 'POST /j_security_check' did not return a 302 but a 200, app is not properly initialized. Page content: id=CD43FCF5268AD1C110B5D1E7D7F7F0D2-n1
Expected :302
Actual   :200
  <Click to see difference>

	at org.testng.Assert.fail(Assert.java:86)
	at org.testng.Assert.failNotEquals(Assert.java:440)
	at org.testng.Assert.assertEquals(Assert.java:110)
	at org.testng.Assert.assertEquals(Assert.java:325)
	at de.javakaffee.web.msm.integration.NonStickySessionsIntegrationTest.testSessionCreatedForContainerProtectedResourceIsStoredInMemcached(NonStickySessionsIntegrationTest.java:943)
	at de.javakaffee.web.msm.integration.NonStickySessionsIntegrationTC8Test.testSessionCreatedForContainerProtectedResourceIsStoredInMemcached(NonStickySessionsIntegrationTC8Test.java:35)
``