Updated Course ID Regex

This regex is nearly identical to the one used by LMS. The only difference is the internal capture groups have been replaced with character sets to avoid issues with the Swagger UI attempting to parse the internal capture groups and pass them along as arguments.

analytics_data_api/v0/urls/courses.py

-import re
-
 from django.conf.urls import patterns, url
 
 from analytics_data_api.v0.views import courses as views
 
-
+COURSE_ID_PATTERN = r'(?P<course_id>[^/+]+[/+][^/+]+[/+][^/]+)'
 COURSE_URLS = [
     ('activity', views.CourseActivityWeeklyView, 'activity'),
     ('recent_activity', views.CourseActivityMostRecentWeekView, 'recent_activity'),
@@ -18,4 +16,5 @@ COURSE_URLS = [
 urlpatterns = []
 
 for path, view, name in COURSE_URLS:
-    urlpatterns += patterns('', url(r'^(?P<course_id>.+)/' + re.escape(path) + r'/$', view.as_view(), name=name))
+    regex = r'^{0}/{1}/$'.format(COURSE_ID_PATTERN, path)
+    urlpatterns += patterns('', url(regex, view.as_view(), name=name))