Also, refactor ESLint and stylelint config files; now everything will work from our root dir.

Update our browserslist.

* Add `last 1 major version` and `>= 1%`.
* Add Firefox.

Firefox v38 is older than the ESR, so basically replace ESR with v38.

Also, include it in the `css` npm script since it's instant.

1. Use the same jQuery version in jspm
2. Update the files to only include the source and dist folders

* Remove the unused assets/js/ie10-viewport-bug-workaround.js.

* Combine ie-emulation-modes-warning.js with docs.min.js.

* rename build/htmllint.js to build/vnu-jar.js
* remove the unused `bash` script
* split the `docs-lint` scripts
* fix watch-js script to run only the parent `js-compile` script

`js-compile` and `js-minify` tasks already call their "children" tasks.

Also, lock babel deps to 7.0.0-beta.2 so that we are on the safe side.