Role Filter Styling

Summary:
* adds double spaces between classes (via front-end style guidelines)

* removes extra active class

* reorganizes `_role-filter.scss` contents & body

* adds transparent `border-bottom` to <li>
	* this prevents the jump around on hover

* adds a `--dropdown` class for dropdown specific styles

* adds padding and width to`<li>` in dropdown button

* adds `.active`, `:hover` & `:active` styles to dropdown button.

* adjusts dropdown pip/triangle color in settings

Test Plan: resize the browser to activate dropdown. click dropdown to see styles.

Reviewers: dkobia, shadowhand

Reviewed By: shadowhand

Differential Revision: https://phabricator.ushahidi.com/D3