[Feature Proposal] Customiseable favicon and sign-in page links

Pretty cool that customisable log-in page was migrated from EE to CE, kudos. Two ideas for taking that further are customisations that I usually make after an update.

• Allow user setting of the favicon (i.e. the logo that shows on a browser tab and bookmark)
• Allow user setting of the links at the bottom left of the page (e.g. I usually have just one link to our own homepage as, for example, I don't want visitors to be able to explore at all if they're not signed in but I do want them to be able to find their way back to our main site)