Quick improvements

- Removed `navigateWith` which wasn't being used anymore
- I think `defaults` should be public and `trigger` should be added to it
- Moved `navigate` up towards the top with the rest of the public stuff
- All the methods use `this` instead of `Backbone.Intercept`
- Switch to using jQuery namespaces like Backbone's `delegateEvents` is a bit cleaner than matching the callbacks (and becomes necessary for `_.bind`-d methods
- Refactors `attr('name') || attr('data-name')` lookup to `_getAttr`
- `trigger !== undefined && trigger === 'foo'` is the same as `trigger === 'foo'`
- quick change to options defaults to make it minify better