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/document_indexing/apps.py

@@ -44,8 +44,8 @@ from .widgets import get_instance_link, index_instance_item_link, node_level
 class DocumentIndexingApp(MayanAppConfig):
     app_namespace = 'indexing'
     app_url = 'indexing'
+    has_tests = True
     name = 'document_indexing'
-    test = True
     verbose_name = _('Document indexing')
 
     def ready(self):