Remove YouTube logo from footer.

Current YouTube logo is not compliant with YouTube's branding
guidelines.

PROD-816

lms/djangoapps/branding/tests/test_api.py

@@ -146,8 +146,6 @@ class TestFooter(TestCase):
                  'icon-class': 'fa-facebook-square', 'title': 'Facebook'},
                 {'url': '#', 'action': 'Follow \xe9dX on Twitter', 'name': 'twitter',
                  'icon-class': 'fa-twitter-square', 'title': 'Twitter'},
-                {'url': '#', 'action': 'Subscribe to the \xe9dX YouTube channel',
-                 'name': 'youtube', 'icon-class': 'fa-youtube-square', 'title': 'Youtube'},
                 {'url': '#', 'action': 'Follow \xe9dX on LinkedIn', 'name': 'linkedin',
                  'icon-class': 'fa-linkedin-square', 'title': 'LinkedIn'},
                 {'url': '#', 'action': 'Follow \xe9dX on Google+', 'name': 'google_plus',

lms/envs/common.py

@@ -2578,7 +2578,7 @@ SOCIAL_SHARING_SETTINGS = {
 SOCIAL_MEDIA_FOOTER_NAMES = [
     "facebook",
     "twitter",
-    "youtube",
+    # "youtube", see PROD-816 for more details
     "linkedin",
     "google_plus",
     "reddit",