Removes Widget section of checklist

We were recommending people use role="application" on the body tag.
This is not advisable.
Adds Color Blindness section

Breaks color blindness into Deuteranopia, Protanopia & Tritanopia while
moving them into their own section in the checklist
Fixes typos in Checklist
Merge branch 'patch-1' of github.com:GuilhermeSimoes/a11yproject.com into GuilhermeSimoes-patch-1
Merge branch 'gh-pages' of github.com:a11yproject/a11yproject.com into gh-pages
checklist tweaks
merging upstream
Updates checklist

Breaks colorblindness into three type. Also fixes typos.
Adds mention of jekyll to about.md
Cleans up wording in about page
Merge branch 'gh-pages' of github.com:bryanstedman/A11Yproject into bryanstedman-gh-pages