UP-3912 Admin UI Updates

https://issues.jasig.org/browse/UP-3912

- Added icons to menu items, made them to look like buttons (so they stand out);
- Updated single-entity-select to look like multi-entity-select (without changing functionality, can still only select one);
- In 'Manage Portlets', updated table nav to Bootstrap styles; added icons to table links;
- Permissions manager looks more like Universailty but Bootstrap-y
Are these rules so broad that they could impact styling from other portlets?   Doesn't seem good that when this view is visible buttons everywhere on the page may get different styling.   Wonder if they shouldn't be more like:

.view-chooseportlet .form-group {}  and .view-chooseportlet .buttons {}