remove duplicate editors.js in asset bundles
z.Storage is needed by editors.js (bug 850193)
npm install during deployment
make LESS mixins and class includes unambiguous
ensure that user-defined slugs get saved during theme submission (bug 845537)
Revert "npm install during deployment"

This reverts commit 89a147b7fa5394691a0d88711ba5c80eadfb20a0.
remove uses of fade in LESS (rgba is nicer and fadeOut works too)