Code style cleanups

Add keyword arguments. Sort arguments and models.
Move literals to their own module. Prepend handler_ to
signal handlers.

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

mayan/apps/django_gpg/settings.py

@@ -7,7 +7,8 @@ from django.utils.translation import ugettext_lazy as _
 
 from mayan.apps.smart_settings import Namespace
 
-namespace = Namespace(name='django_gpg', label=_('Signatures'))
+namespace = Namespace(label=_('Signatures'), name='django_gpg')
+
 setting_gpg_home = namespace.add_setting(
     global_name='SIGNATURES_GPG_HOME',
     default=os.path.join(settings.MEDIA_ROOT, 'gpg_home'),