Remove dev_int LMS env settings

This contains hard-coded reference to out-dated courses.

lms/envs/dev_int.py

-"""
-This enables use of course listings by subdomain. To see it in action, point the
-following domains to 127.0.0.1 in your /etc/hosts file:
-
-  berkeley.dev
-  harvard.dev
-  mit.dev
-
-Note that OS X has a bug where using *.local domains is excruciatingly slow, so
-use *.dev domains instead for local testing.
-"""
-
-# We intentionally define lots of variables that aren't used, and
-# want to import all variables from base settings files
-# pylint: disable=wildcard-import, unused-wildcard-import
-
-from .dev import *
-
-FEATURES['SUBDOMAIN_COURSE_LISTINGS'] = True
-
-COURSE_LISTINGS = {
-    'default': ['BerkeleyX/CS169.1x/2012_Fall',
-                'BerkeleyX/CS188.1x/2012_Fall',
-                'HarvardX/CS50x/2012',
-                'HarvardX/PH207x/2012_Fall',
-                'MITx/3.091x/2012_Fall',
-                'MITx/6.002x/2012_Fall',
-                'MITx/6.00x/2012_Fall'],
-
-    'berkeley': ['BerkeleyX/CS169.1x/2012_Fall',
-                 'BerkeleyX/CS188.1x/2012_Fall'],
-
-    'harvard': ['HarvardX/CS50x/2012'],
-
-    'mit': ['MITx/3.091x/2012_Fall',
-            'MITx/6.00x/2012_Fall']
-}