Polish and clean-up

Resolving issues in #30.

- [x] clean up the section around the vimeo video.
- [x] clean up the email sign up forms
- [x] final badge award slide backpack needs to be centered.
- [x] add top and bottom lines to 'what are badges' section
- [x] add top and bottom lines to 'earn a badge' section
- [x] format button in 'earn a badge' section