Start context menu directive

Still some details to carve out
Add proper position to contextMenu directive
Hold a reference to the current menu in a factory

Because we now inject an element, we have a real reference to it and
can detect when another menu is open. Before this change we would open
up several ones at the same time.
Remove obsolete code
Add css for context menus
Use offset() not position() in context menu
Add some style to the context menu
Start to render context menus
Add context menu handling in plugin conf
Add context menu conf for morph in staging2
Make plugins with menus known in MainCtrl
Allow multi line strings in jshintrc
Delete a forgotten console.log
Pass plugins and state to arethusaContextMenu
Add pluginContextMenu directive
And morph menu template, fix its path in staging2
Render plugin specific context menu content