Analytics/Epics/Wikimetrics cohort sharing

= Goals = To facilitate the sharing of cohorts between Wikimetrics users who are working on the same project, and to provide a basic set of user rights that allow Wikimetrics product owners to view other users' cohorts and reports, and make changes if necessary for Legal or housekeeping reasons.

= Users =

= Use cases =

High priority

 * 1) As a Wikimetrics user, I need to be able to share a cohort with other users who are working on the same project to prevent duplicate work and "forking" of datasets.
 * 2) As a Wikimetrics Admin, I need to know if people are uploading invalid, spam or junk data into the system and delete it.
 * 3) As a Wikimetrics Admin, I need to know if people are uploading data that violates WMF legal policies and be able delete it.

Later

 * 1) As a Wikimetrics Admin, I need to be able to occasionally add and remove tags to/from cohorts for housekeeping reasons.