Hide service user icon and avatar when in mobile or tablet view

Closes #1435, closes #1442
Center header bar on mobile views, and minimize margins/spacing on mobile devices
Closes #1436, closes #1445
Don't show any registration status on log in form if registration is disabled.
Hide Registration link if on phone
Closes #1437, closes #1444
Hide most footer elements on phone & tablet views; update copyright notice.
Closes #1438, closes #1441