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)
``