adds test for controlled Radio with checkedLink.

As we have tests for controlled checkboxes and text inputs, from a suggestion of syranide this commit adds a test for radio inputs.
It tests for controlling the true and the false state. This is needed because radio input will remain checked by default if they start checked. Being controlled or not this HAS to happen (spec). When starting with false, if we want to control it we expect that the radio remains false even trying to set it to true.
This commit adds a spec for the above.