568 - Specialized autosuggest feed for finding principals to share content with
568 - Added canInteract validation on the createDiscusion, createContent and setContentPermissions API methods
#568 - Follow-up

 * _.isEmpty in the appropriate places
 * cleaned up unit test
 * refactored documentation
Merge pull request #568 from simong/568-share-feed

Groups who are private and joinable show up in share feed, yet you cannot share with them