Use Google fonts & local assets

Before, the stylesheet linked to the fonts on Roon's S3 bucket. @cobbspur asked me to stop linking to that (good call!). I got Source Sans Pro from Google Fonts. For Filo Pro and Gibson, I added the files to the repo. 

I'm not sure if distributing Filo Pro and Gibson here is legal. Someone should check. Someone should probably email Drew and ask if using Pictos here is also okay. I'm sure it is, but no harm in double checking.