New tab (Metrics) in instructor dashboard

Metrics tab shows student data:
  -Count of students opened a subsection
  -Grade distribution per problem

for each section/subsection of the course.

Implemented for both the old and beta dashboard
Controlled by a feature flag 'CLASS_DASHBOARD'
Data is aggregated across all students
Aggregate data computed from courseware_studentmodule

lms/envs/common.py

@@ -1246,6 +1246,11 @@ VERIFY_STUDENT = {
     "DAYS_GOOD_FOR": 365,  # How many days is a verficiation good for?
 }
 
+### This enables the Metrics tab for the Instructor dashboard ###########
+FEATURES['CLASS_DASHBOARD'] = False
+if FEATURES.get('CLASS_DASHBOARD'):
+    INSTALLED_APPS += ('class_dashboard',)
+
 ######################## CAS authentication ###########################
 
 if FEATURES.get('AUTH_USE_CAS'):

lms/envs/dev.py

@@ -279,10 +279,12 @@ CC_PROCESSOR['CyberSource']['PURCHASE_ENDPOINT'] = os.environ.get('CYBERSOURCE_P
 ########################## USER API ########################
 EDX_API_KEY = None
 
-
 ####################### Shoppingcart ###########################
 FEATURES['ENABLE_SHOPPING_CART'] = True
 
+### This enables the Metrics tab for the Instructor dashboard ###########
+FEATURES['CLASS_DASHBOARD'] = True
+
 #####################################################################
 # Lastly, see if the developer has any local overrides.
 try:

lms/envs/test.py

@@ -269,6 +269,9 @@ PASSWORD_HASHERS = (
     # 'django.contrib.auth.hashers.CryptPasswordHasher',
 )
 
+### This enables the Metrics tab for the Instructor dashboard ###########
+FEATURES['CLASS_DASHBOARD'] = True
+
 ################### Make tests quieter
 
 # OpenID spews messages like this to stderr, we don't need to see them: