Add logo image to home page

[sirilyan]

• set up your cool logo image URL in control panel and it'll appear in the corner of the non-logged-in homepage
• your instance's hostname will be a subtitle of the main goblin logo

MUSTFIX:

• logo now looks weird once you're actually logged in
• add the Bookman clone font for embedding (local hosting is preferable to cloud)
• haven't even looked at mobile and tablet views yet

[sirilyan]

Also, the goblin logo on the sidebar was being hidden by your profile background, and now it's not:

The SCSS should be properly scoped/limited, but right now I've just got it at the top level. Trying to work on that.

[sirilyan]

Good to go!