When non-hypothesis users(or logged out users) are viewing a direct linked
annotation, we want to help them understand what they are looking at and
encourage them to sign up(or sign in).

Display a CTA message when:
* user is logged out
* user has landed on a DL
* there is a selection
* user has permissions to view the selection

Also,
* Add logo svg
* Update icomoon css
* Pull variables\.scss from 03cbef2