Add markup and copy for open-source community section

* Add basic style layout for the community section
* Add community icons
* Change layout of the community section
* Add button to section and clean up responsive style
* Uncomment social links in landing page
* Move stylesheets to modules folder
* Add global nav partial to index and featured social media links
* Remove community icons and restructure community section
* Add width to subtitle, call in locales, and reduce font size
* Reduce footer p size
* Refactor community code after PR with improving names of links, etc.
Add first pass of Introduction section of landing page

* Lay out text and browser for the Intro section
* Use flexbox to style for responsive mobile
* Create locales for the copy in Intro

https://trello.com/c/lOVhegcG
Remove vendor prefixes so that autoprefixer can automate that

https://trello.com/c/lqPnkt7M
Style and place search bar in docs

* Style documentation nav links
* Move search bar to partial
* Reduce spacing in doc nav items
* Refactor start a new site doc