WIP: Fields without bootstrap

[kparkov]

Also triggers on the change event, which will make it easier to validate on blur.

Fixes #74.

[kparkov]

TODO

• Be able to connect to certain events, such as keypress.
• Avoid multiple triggering of update event.
• Expose the clean event (maybe through another event name), so we can use modifiers on that event.
• Retain backwards compatibility.