[editor] HuePubSub subscribes are only bound to the first opened editor

$(document).ready is only called once for the editors, registering the pubsub topics to the initial editor type.

If first editor has url params ?type=impala all the pubsubs are registered for 'editor-impala', when switching to another editor the pubsubs doesn't exist for that type and are not triggered anymore.

This means we have to move all the pub subs to the top level viewmodel (only loaded once) and avoid subscribing from within snippets etc.