remove `value` validation in <RadioGroup>
remove `value` validation in <RadioGroup>

it's redundant since we already require it in <Radio> propTypes

yldio/copilot,yldio/joyent-portal,yldio/joyent-portal,yldio/copilot,yldio/copilot,geek/joyent-portal,geek/joyent-portal