Using 12s as timeout for all tests, as a workaround for #146.

org.sat4j.core/src/test/java/org/sat4j/ModelIteratorTest.java

@@ -383,7 +383,7 @@ public class ModelIteratorTest {
         }
     }
 
-    @Test(timeout = 6000)
+    @Test(timeout = 12000)
     public void testGlobalTimeoutCounter() {
         SolutionCounter counter = new SolutionCounter(
                 SolverFactory.newDefault());