Added explicit logout link in the agreement box

Fixes bug 2932.
Update UI elements when going back in the browser history

Since browsers implement a back/forward cache, when a page is loaded
from the cache breadcrumbs won't reflect the page's current status.
Therefore it's necessary to alter its state when the page is loaded from
the cache. Unfortunately all browser's don't properly support `pageshow`
event's `persisted` property, so we are running this code for every page
load.

Fixes bug 2949.
Adjusted shadow for forms displayed in lightbox popups
Fixed select2 value setting call