Revert "Add checkedValue binding that works with the checked binding to allow for arbitrary values for checkboxes and radio buttons."

This reverts commit 4db92498ff293d57b2626254b9c33d580f098bea.
Merge pull request #973 from knockout/954-remove-2.3.0-checkedValue

Revert "Add checkedValue binding"
Increase timeouts in tests so that they pass in Firefox.
Merge pull request #967 from knockout/967-fix-tests-failing-in-ff

/spec/runner.html failure
If the optionsCaption value is null or undefined, don't show the caption.
add a test for undefined that also needs to unwrap the observable
Merge pull request #997 from knockout/997-deactivate-caption

Computed optionsCaption not disappearing fully in latest build
Update version to 2.3.0rc
Merge remote-tracking branch 'upstream/master'