CLC-4524 - Bye Compass, Welcome Autoprefixer! - Update Gemfile

https://jira.ets.berkeley.edu/jira/browse/CLC-4524
CLC-4524 - Bye Compass, Welcome Autoprefixer! - Update SCSS Lint

https://jira.ets.berkeley.edu/jira/browse/CLC-4524
CLC-4524 - Bye Compass, Welcome Autoprefixer! - Add config file

https://jira.ets.berkeley.edu/jira/browse/CLC-4524
CLC-4524 - Bye Compass, Welcome Autoprefixer! - Update CSS files

https://jira.ets.berkeley.edu/jira/browse/CLC-4524
Merge pull request #3154 from christianv/CLC-4524

CLC-4524 - Bye Compass, Welcome Autoprefixer!