Update fonts

[madprime]

Update the fonts supported to Merriweather and Montserrat, and remove unnecessary fonts.

This can also switch to using fonts hosted on our static server: https://github.com/OpenHumans/oh-static

Description

The site is supposed to be using Montserrat, but apparently I failed to actually add the font.

Based on the CSS here and here, the site needs the following fonts:

• Merriweather
• Montserrat (missing)
• Ubuntu

However according to the base HTML template here we're actually supporting

• Quando (obsolete)
• Merriweather
• Open Sans (obsolete)
• Ubuntu