Introduce gr-permission

This element houses rules for a particular project access section.

Here is the access hierarchy:

Project access
- Sections
  - Permissions <-- This is the component for this change
    - Rules

It has the ability to add new rules, or remove itself (with an undo
option).
Rules that already exist in a particular permission will not be present
in the autocomplete options.

Change-Id: I4db09d1a8bb7f738dff771867d25fce424a3ea3a

polygerrit-ui/app/scripts/util.js

@@ -58,6 +58,5 @@
     // Character is an ellipsis.
     return '\u2026/' + pathPieces[pathPieces.length - 1];
   };
-
   window.util = util;
 })(window);