Add keyboard support - Githubissues

[ ] Escape button should close dialog window.
- For alert dialog it should be accept closing
- For confirm dialog it should be decline closing
- For blank dialog it shouldn't close it
[ ] Enter button should close dialog window
- For alert dialog it should be accept closing
- For confirm dialog it should be accept closing
- For blank dialog it shouldn't close it
[ ] Make tests for it
[ ] Add tutorial page "Hotkeys"

wheely / ember-dialog