Fix manage.py to ouput the help of the django command if requested

Commands like the following were not working correctly:
```
$ python manage.py lms runserver --lms
```

manage.py

@@ -20,7 +20,7 @@ from argparse import ArgumentParser
 def parse_args():
     """Parse edx specific arguments to manage.py"""
     parser = ArgumentParser()
-    subparsers = parser.add_subparsers(title='system', description='edx service to run')
+    subparsers = parser.add_subparsers(title='system', description='edX service to run')
 
     lms = subparsers.add_parser(
         'lms',
@@ -31,8 +31,8 @@ def parse_args():
     lms.add_argument('-h', '--help', action='store_true', help='show this help message and exit')
     lms.add_argument(
         '--settings',
-        help="Which django settings module to use from inside of lms.envs. If not provided, the DJANGO_SETTINGS_MODULE "
-             "environment variable will be used if it is set, otherwise will default to lms.envs.dev")
+        help="Which django settings module to use under lms.envs. If not provided, the DJANGO_SETTINGS_MODULE "
+             "environment variable will be used if it is set, otherwise it will default to lms.envs.dev")
     lms.add_argument(
         '--service-variant',
         choices=['lms', 'lms-xml', 'lms-preview'],
@@ -52,8 +52,8 @@ def parse_args():
     )
     cms.add_argument(
         '--settings',
-        help="Which django settings module to use from inside cms.envs. If not provided, the DJANGO_SETTINGS_MODULE "
-             "environment variable will be used if it is set, otherwise will default to cms.envs.dev")
+        help="Which django settings module to use under cms.envs. If not provided, the DJANGO_SETTINGS_MODULE "
+             "environment variable will be used if it is set, otherwise it will default to cms.envs.dev")
     cms.add_argument('-h', '--help', action='store_true', help='show this help message and exit')
     cms.set_defaults(
         help_string=cms.format_help(),
@@ -62,7 +62,6 @@ def parse_args():
         service_variant='cms'
     )
 
-
     edx_args, django_args = parser.parse_known_args()
 
     if edx_args.help:
@@ -79,11 +78,13 @@ if __name__ == "__main__":
         os.environ["DJANGO_SETTINGS_MODULE"] = edx_args.settings_base.replace('/', '.') + "." + edx_args.settings
     else:
         os.environ.setdefault("DJANGO_SETTINGS_MODULE", edx_args.default_settings)
+
     os.environ.setdefault("SERVICE_VARIANT", edx_args.service_variant)
+
     if edx_args.help:
         print "Django:"
         # This will trigger django-admin.py to print out its help
-        django_args.insert(0, '--help')
+        django_args.append('--help')
 
     from django.core.management import execute_from_command_line