Redesign website based on figma mockup

This is a larger, epic issue to track the redesign of our homepage, based on the figma mockup:

https://www.figma.com/file/M6CBFDhpoapozWxn3qxrTZ/CfP

Issues:

* (keeping as is) https://github.com/CodeForPhilly/codeforphilly.org/issues/92
* #94 
* #95 