fixes https://github.com/twbs/bootstrap/issues/13367

Second color stop value should be percentage instead of decimal value.
Update JSZip to v2.2.1.
Update holder.js to v2.3.2.
Run `grunt`.
Merge pull request #13424 from twbs/docs-libs

Update docs libs
Merge pull request #13437 from saas786/master

fixes #13367