Docs build script (#3332)

* Remove artifacts from repo

* Remove docs stuff from build script

* Add new docs build script

* Add 'third-party' shim in playground worker

* Build from src if it's a PR

* Add command to package.json and remove old stuff from travis

.gitignore

@@ -9,6 +9,7 @@
 /website/node_modules
 /website/build
 /website/i18n
+/website/static/lib
 .DS_Store
 coverage
 .idea