Refactored all profile paths.

All profile paths are of the form:
/<resource type>/<tenant alias>/<resource id>

Examples:
 * /user/gt/VPlyuTp1sf
 * /group/nyu/eVynpeg0LM
 * /content/cam/VT-kmVy0s5
 * /discussion/pmc/TVUvDVp0cf
Merge master in issue-429-messagebox-entity-urls
Merge master in issue-429-messagebox-entity-urls
Renamed groupAlias across all test files to something more appropriate.
Made displayName a non-optional property in the group model
Fixed failing test for limiting discussion messages.
Added the correct profile paths for discussion objects.
Simplified lines