#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* Cleanup: remove outdated warning for session timeout = 0
- Remove outdated warning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/main/java/fr/xephi/authme/datasource/CacheDataSource.java

@@ -208,6 +208,21 @@ public class CacheDataSource implements DataSource {
         source.setUnlogged(user.toLowerCase());
     }
 
+    @Override
+    public boolean hasSession(final String user) {
+        return source.hasSession(user);
+    }
+
+    @Override
+    public void grantSession(final String user) {
+        source.grantSession(user);
+    }
+
+    @Override
+    public void revokeSession(final String user) {
+        source.revokeSession(user);
+    }
+
     @Override
     public void purgeLogged() {
         source.purgeLogged();