Merge pull request #541 from edx/e0d/escalated-priv-migrations

adding migrate env for cms

cms/envs/aws_migrate.py

+"""
+A Django settings file for use on AWS while running
+database migrations, since we don't want to normally run the
+LMS with enough privileges to modify the database schema.
+"""
+
+# We intentionally define lots of variables that aren't used, and
+# want to import all variables from base settings files
+# pylint: disable=W0401, W0614
+
+# Import everything from .aws so that our settings are based on those.
+from .aws import *
+import os
+from django.core.exceptions import ImproperlyConfigured
+
+USER = os.environ.get('DB_MIGRATION_USER', 'root')
+PASSWORD = os.environ.get('DB_MIGRATION_PASS', None)
+
+if not PASSWORD:
+    raise ImproperlyConfigured("No database password was provided for running "
+                               "migrations.  This is fatal.")
+
+DATABASES['default']['USER'] = USER
+DATABASES['default']['PASSWORD'] = PASSWORD