mattdrayer/api-groups-organizations-list: Support for viewing related orgs

merged with master and updated url
new api to get list of workgroups by group
Merge pull request #108 from edx-solutions/ziafazal/user-count-by-city

user count by city and users enrolled in a course
course leaders by points_scored

updated urls

updated docs
Merge pull request #110 from edx-solutions/ziafazal/course-proficiency-leaderboard

course leaders by points_scored
Updated Group Project XBlock Hash
Merge pull request #111 from edx-solutions/ziafazal/get-workgroups-of-a-group

new api to get list of workgroups by group - LGTM :+1: merging to allow group project XBlock to access it
Group Poejct XBlock update to use new API endpoint
mattdrayer/api-currentcontentid: GET response now returns content identifier for current position
mattdrayer/api-currentcontentid: Added position_tree to response