Customizer: switch to UglifyJS2 (v2.4.13).

The uglify build is generated with `uglifyjs --self -o uglify.min.js`.
Add the jquery check in customizer's output.
Add the license header in the non minified build too.
Run `grunt`.
fixes #11099 - $.collapse() overrides the original dimension of the coll...
fixes #13296 Dropdown disappears with right-click on Firefox
Added specificity note to docs per issue #13332
Fixed typo and added leading space
grunt dist
fixes #13365: remove dupe css in grid example
Merge pull request #13358 from Jakobovski/docs-improvements-#13332

Added specificity note to docs per issue #13332
fix #13360 by making deprecation notices visible in customizer
fix #13337 by mentioning removal of .progress-* contextual classes
quote data-* attribute value in docs JS per best-practices
Merge pull request #13373 from twbs/fix-13360

Make variable deprecation notices visible in customizer
quote attribute value in selector in offcanvas.js
quote attribute value in selector in JS docs example
quote attribute values in selectors in JS unit tests for consistency
rename jquery.js -> jquery.min.js since it's minified
Merge pull request #13381 from twbs/vendor-jquery-min

rename jquery.js -> jquery.min.js since it's minified