MUMPO-1417: Change side menu question mark with circle to just question mark

Angular side of this (click link for screenshots) : https://github.com/UW-Madison-DoIT/uPortal/pull/290
Change the side menu question mark icon to a question mark without a circle. Unfortunately there was no glyphicon for a question mark without a circle, so I changed it to a font awesome question mark. For consistent looks across all the icons, I changed all the side menu icons from glyphicons to font awesome icons.
The fa-fw was to keep the fixed width.