Hide user login details from non-admins

Summary:
- Add global user object to App
- Check the user role before displaying login details

Refs T682

Depends on D335

Test Plan: Try viewing settings/users as admin and non-admin

Reviewers: bodacea, rjmackay, shadowhand

Reviewed By: shadowhand

Subscribers: shadowhand

Maniphest Tasks: T682

Differential Revision: https://phabricator.ushahidi.com/D336