Manage Users

Summary:
* revises users.html to match Design Framework
https://docs.google.com/a/ushahidi.com/document/d/1JnfDERRFBV6suR0lglf76Fu9uVnfhs0PjwiGrtWrHDU/edit#heading=h.fvsdg5y0xng0

Admin can: (after the below todos are complete)
  * select users
  * delete users
  * change user's role
  * edit user by clicking user name
  * add user by clicking "add user"

Todo:
* `ng-model` on checkboxes is not working, has to do with scope. The intended behaviour is checking user enables "delete" and "change role"
* clicking user name needs to route to edit view (dev task?)
* clicking "add user" button needs to route to add user form (dev task?)

Fixes T1193

Test Plan:
* check layout
* need help with todos

Reviewers: rjmackay, brandonrosage, shadowhand

Reviewed By: shadowhand

Subscribers: spaudanjo, sebm90, dkobia

Maniphest Tasks: T1193

Differential Revision: https://phabricator.ushahidi.com/D558