Simplify test runner by adding a new option '--mayan-apps' that

automatically tests all Mayan apps that report to have tests.
Change the app flag that indicates when an app has test
from 'test' to the more explicit 'has_test'.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/authentication/apps.py

@@ -12,8 +12,8 @@ logger = logging.getLogger(__name__)
 
 
 class AuthenticationApp(MayanAppConfig):
+    has_tests = True
     name = 'authentication'
-    test = True
     verbose_name = _('Authentication')
 
     def ready(self):