feat(bsSwitch): turn off radio button, honor ngTrueValue/ngFalseValue

Add `switch-radio-off` option to enable toggling a radio button from `true` to `false`.
Honor `ngTrueValue`/`ngFalseValue` for the model value.
Update to angular-1.2.22.
Test on Firefox, Chrome, IE, PhantomJS.

Requires https://github.com/nostalgiaz/bootstrap-switch/pull/349 to be merged upstream.

Fix #24.