Theme master

Sass overhaul, though layout remains the same.

#### Changes

- "Billboard" (jumbotron) spacing on front page and project page
- "Glass" project thumbnails
- Larger text
- Matching masthead text size
- Unified link styling. Links can be:
  - By default, brand color, darkened & underlined on hover
  - `title-link`: Black, gray rounded background on hover
  - `text-muted`: turns links gray and italic
  - `card-link` for clickable divs with gray highlight
- Update project leader rows:
  - Now responsive on mobile
  - Consistent spacing
  - Circle avatars for people
- More saturated "success" button color
- Replace start project icon
- Fix layout bugs
- Adjust `body` padding
- Fix button margins (applied as necessary)
- Fix image margins (applied as necessary)
- Fix disclosure form margins

#### Remaining tasks

- Footer will be added in a separate PR
- Tumblr theme should be updated after this is deployed (easiest way)

#### Reviewing this PR

Given the scope of this PR, weight whether fixes on this branch or updating minor details in a separate issue is more appropriate. :heart: :cat:

Temporarily, I have a demo of the changes up at http://beta.teslaworks.net/ for the enjoyment of @wagne763 and @laugh039. Feel free to check it out and leave your comments here.

Thanks all!