Print stacktraces for unexpected errors in tests

Couple tests that kill DB fail with command line exceptions.

Author: lutovich

driver/src/test/java/org/neo4j/driver/v1/integration/SessionAsyncIT.java

@@ -199,6 +199,7 @@ public void shouldFailWhenServerIsRestarted()
         }
         catch ( Throwable t )
         {
+            t.printStackTrace();
             assertThat( t, instanceOf( ServiceUnavailableException.class ) );
         }
     }

driver/src/test/java/org/neo4j/driver/v1/integration/TransactionAsyncIT.java

@@ -593,6 +593,7 @@ public void shouldFailWhenServerIsRestarted() throws IOException
         }
         catch ( Throwable t )
         {
+            t.printStackTrace();
             assertThat( t, instanceOf( ServiceUnavailableException.class ) );
         }
     }