Fix unused-import errors

cms/djangoapps/contentstore/views/dev.py

@@ -5,8 +5,6 @@ in a 404 error.
 """
 # pylint: disable=unused-argument
 from edxmako.shortcuts import render_to_response
-from mako.exceptions import TopLevelLookupException
-from django.http import HttpResponseNotFound
 
 
 def dev_mode(request):

cms/djangoapps/contentstore/views/helpers.py

@@ -9,10 +9,9 @@ import urllib
 
 from django.conf import settings
 from django.http import HttpResponse
-from django.shortcuts import redirect
 from django.utils.translation import ugettext as _
 
-from edxmako.shortcuts import render_to_string, render_to_response
+from edxmako.shortcuts import render_to_string
 from opaque_keys.edx.keys import UsageKey
 from xblock.core import XBlock
 import dogstats_wrapper as dog_stats_api

cms/djangoapps/contentstore/views/preview.py

@@ -27,7 +27,6 @@ from xblock.runtime import KvsFieldData
 from xblock.django.request import webob_to_django_response, django_to_webob_request
 from xblock.exceptions import NoSuchHandlerError
 from xblock.fragment import Fragment
-from student.auth import has_studio_read_access, has_studio_write_access
 from xblock_django.user_service import DjangoXBlockUserService
 
 from lms.djangoapps.lms_xblock.field_data import LmsFieldData

cms/djangoapps/contentstore/views/tests/test_course_index.py

@@ -10,7 +10,6 @@ import pytz
 
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
-from django.test.utils import override_settings
 from django.utils.translation import ugettext as _
 
 from contentstore.courseware_index import CoursewareSearchIndexer, SearchIndexingError