[SD-1119] Adding default role to new user.
(fix:delete roles that still have users) [SD-1118] Add atribute to role to indicate default role
Merge pull request #383 from akintolga/feat-privilege

feat(privilege) [SD-1123] Provide  API response for the User Privileges
Merge branch 'feat-privilege' of https://github.com/superdesk/superdesk-server into feat-privilege
Merge remote-tracking branch 'upstream/feat-privilege' into feat-privilege
fix(privileges): use `:` instead of `.` as separator

there is a mongo error when using `.` as a separator and patching users
with `{"archive.spike": 1}`

SD-1117
feat(privileges): add privileges to user schema

SD-1091
fix(privileges): send all privileges for admin user

SD-1123
fix(privileges): raise exception for privilege with invalid name
Merge remote-tracking branch 'andrew/feat-privilege' into feat-privilege
Merge remote-tracking branch 'mayur/feat-privilege' into feat-privilege

Conflicts:
	apps/users/services.py
[SD-1119] fixing the code are merge conflict.

close #389
[SD-1122] Refactoring the check permissions
Merge branch 'feat-privilege' of https://github.com/superdesk/superdesk-server into feat-privilege
[SD-1122] Authorization improvements and added missing privileges