Update background-img-opts.json
Update background-img-opts.json

removed trailing "17"
Added 'Known Issue' to contentsecuritypolicy
Update viewport-units.json

Did not know where to add buggyfill description, added to title
Update viewport-units.json
WebVTT disabled in Firefox 29 and 30
Merge pull request #511 from sladex/patch-3

Update background-img-opts.json
Merge pull request #512 from mkurz/contentsecuritypolicy_fix

Added 'Known Issue' to contentsecuritypolicy for Internet Explorer
Merge pull request #513 from Forkest/patch-1

Update viewport-units.json
Merge pull request #515 from mpopp75/fx-webvtt

WebVTT disabled in Firefox 29 and 30