Better support radio inputs in bindProperty and config forms actions.

$.fn.bindProperty() now accepts a radioValue option. If set, this will
manage standard radio behavior between radio input elements and a model
property. Each input is expected to have bindProperty() called on it,
passing a radioValue corresponding to the appropriate value in the
model's property.

When the element's property (which is expected to be a boolean) changes
to true, the model's property will be set to the radioValue. Otherwise,
to prevent conflicts, nothing will be set on the model (with the
expectation being that another bindProperty() will handle the radio
input that's now checked).

When the model's property changes, the value will be compared against
the radioValue. If they match, the radio input will be checked.

The new radio action support for config form list items now support
taking a radioValue, which is then passed to bindProperty.

Reviewed at https://reviews.reviewboard.org/r/6160/
Merge branch 'release-0.8.x'
Bump to 0.8.9 dev.
Merge branch 'release-0.8.x'