Changed SSH User and Port Popup Style, also

- Added a message that shows previous user and port fail
- Moved inline css to a css file
- Changed a little bit the way we handle the popup and its data
Merge branch 'ssh_userPort' of github.com:mistio/mist.io into ssh_userPort

Conflicts:
	src/mist/io/static/js/app/controllers/keys.js