[keycloak-dev] Moved user session model tests to testsuite/integration

[Stian Thorgersen]

I moved UserSession related tests to:

  https://github.com/stianst/keycloak/blob/master/testsuite/integration/src/test/java/org/keycloak/testsuite/model/UserSessionProviderTest.java
 
The reason is that UserSession tests rely on Realms and Users so need a ModelProvider to run. It also makes it easier to run it with different configurations.

I think we should move the rest of the tests in model/tests to the same place. This will help once we split the model into RealmProvider and UserProvider.

If everyone is happy with this I can do it next week.