Working CopyHTML shortcut

closes #3481
- Pressing Ctrl/CMD+Shift+C in the editor will open up a modal that
contains the generated HTML for either the selected text or the whole
post
Rather than taking two steps, one to bind and another to pass params, may i suggest `call` or `apply`?

`modalController.set.call(modalController, 'generatedHTML', generatedHTML)`
or
`modalController.set.apply(modalController, ['generatedHTML', generatedHTML])`