Adding in a new radio input helper.

[jwoertink]

Purpose

Fixes #1023

Description

This adds in a missing radio helper method

para "What's your favorite framework?"
label_for(op.question, "Lucky")
radio(op.question, "lucky")
label_for(op.question, "Rails")
radio(op.question, "rails")
label_for(op.question, "Sails")
radio(op.question, "sails")
label_for(op.question, "Grails")
radio(op.question, "grails")

Checklist

• - An issue already exists detailing the issue/or feature request that this PR fixes
• - All specs are formatted with crystal tool format spec src
• - Inline documentation has been added and/or updated
• - Lucky builds on docker with ./script/setup
• - All builds and specs pass on docker with ./script/test

[paulcsmith]

Lookin good! I’m glad you’re done with classes :D I’m digging all these PRs