#1031 Introduce hasSession field in datasource (#1351)

* Introduce hasSession field in datasource

That makes isLogged more consistent as it will be '1' only when the player is online.

* Fixes

* Fix unit testing

* Update config doc

* Create SessionService

* Create test for SessionService, avoid DB operations if sessions are disabled

* Cleanup: remove outdated warning for session timeout = 0
- Remove outdated warning
- Encapsulate session enabled check in SessionService

* Fix failing SessionServiceTest, add data source integration tests for session methods

src/test/java/fr/xephi/authme/command/executable/authme/RegisterAdminCommandTest.java

@@ -144,7 +144,6 @@ public class RegisterAdminCommandTest {
         ArgumentCaptor<PlayerAuth> captor = ArgumentCaptor.forClass(PlayerAuth.class);
         verify(dataSource).saveAuth(captor.capture());
         assertAuthHasInfo(captor.getValue(), user, hashedPassword);
-        verify(dataSource).setUnlogged(user);
     }
 
     @Test
@@ -174,7 +173,6 @@ public class RegisterAdminCommandTest {
         ArgumentCaptor<PlayerAuth> captor = ArgumentCaptor.forClass(PlayerAuth.class);
         verify(dataSource).saveAuth(captor.capture());
         assertAuthHasInfo(captor.getValue(), user, hashedPassword);
-        verify(dataSource).setUnlogged(user);
         verify(player).kickPlayer(kickForAdminRegister);
     }