Add signer tests for verifying presentation

Added due to update of the Signer service to verify presentations.
Verifying credential is not needed at the moment and this is the reason it is not fully functioning.
The negative tests are WIP due to bug

src/main/java/core/ResponseContainer.java

@@ -17,8 +17,6 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 package core;
 
-import core.*;
-
 import java.util.ArrayList;
 import java.util.List;