Change keyboard shortcut context

closes #4247
- added scope to every shortcut, the scope of shortcut is default to
  'default'
- add shortcut `enter` to modal which confirm the modal
- shortcut `enter` and `esc` now have scope 'modal'
- when lunch a modal, scope is switching to 'modal', and set back to
  'default' when close
- shortcut `enter` now confirm the dialog without conflicting with route
  shortcuts
Ah, I just noticed that the code style's a little off for how we maintain things. @hswolff we no testy this?

Anyways, can you move your colons next to their keys? `'esc': {action: 'closePopups', scope: 'modal'}`