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/common/apps.py

@@ -71,8 +71,8 @@ class MayanAppConfig(apps.AppConfig):
 
 class CommonApp(MayanAppConfig):
     app_url = ''
+    has_tests = True
     name = 'common'
-    test = True
     verbose_name = _('Common')
 
     def ready(self):