Switch to full app paths

Instead of inserting the path of the apps into the Python app,
the apps are now referenced by their full import path.

This solves name clashes with external or native Python libraries.
Example: Mayan statistics app vs. Python new statistics library.

Every app reference is now prepended with 'mayan.apps'.

Existing config.yml files need to be updated manually.

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

mayan/apps/task_manager/apps.py

@@ -2,11 +2,11 @@ from __future__ import unicode_literals
 
 from django.utils.translation import ugettext_lazy as _
 
-from common import (
+from mayan.apps.common import (
     MayanAppConfig, menu_object, menu_secondary, menu_tools
 )
-from common.widgets import TwoStateWidget
-from navigation import SourceColumn
+from mayan.apps.common.widgets import TwoStateWidget
+from mayan.apps.navigation import SourceColumn
 
 from .classes import CeleryQueue, Task
 from .links import (
@@ -20,7 +20,7 @@ class TaskManagerApp(MayanAppConfig):
     app_namespace = 'task_manager'
     app_url = 'task_manager'
     has_tests = True
-    name = 'task_manager'
+    name = 'mayan.apps.task_manager'
     verbose_name = _('Task manager')
 
     def ready(self):