Added Tern and Acorn libraries
Basic implementation
Loading only for js, customise css and fadeout
Added functionality to start tern server and load definitions
Added complete url to files
Removed old hint and connected Tern to tab keybinding.
Functionality when Tern is disabled
Removed emmet key handlers from javascript panel and fixed autocomplete function accordingly.
Removed emmet toggle comment for javascript and implemented the CodeMirror one.
Changed tooltip appearance to jsbin style.
Added feature flag and moved the functionality to its own file.
Added user tern setting, moved definition lists to its own file, better regex.
Merge branch 'master' into feature/1216-tern-support

Conflicts:
	lib/features.js
Changed tern access from editor to addons
Merge pull request #1255 from jsbin/feature/1216-tern-support

Feature/1216 tern support