[fix] robot tests

searx/settings_robot.yml

 general:
     debug : False
+    instance_name : "searx_test"
 
 search:
     safe_search : 0
   - name : general_dummy
     engine : dummy
     categories : general
+    shortcut : gd
 
   - name : dummy_dummy
     engine : dummy
     categories : dummy
+    shortcut : dd
 
 locales:
     en : English

searx/testing.py

         )
 
     def tearDown(self):
-        os.kill(self.server.pid, 15)
+        os.kill(self.server.pid, 9)
         # remove previously set environment variable
         del os.environ['SEARX_SETTINGS_PATH']
 
 
     base_dir = abspath(join(dirname(__file__), '../tests'))
     if sys.argv[1] == 'robot':
-        Runner(['--color',
-                '--auto-progress',
-                '--path', base_dir],
-               found_suites=[test_suite()]).run()
+        r = Runner(['--color',
+                    '--auto-progress',
+                    '--stop-on-error',
+                    '--path',
+                    base_dir],
+                    found_suites=[test_suite()])
+        r.run()
+        sys.exit(int(r.failed))