Updating Frontity dependencies for development and hacking singular option checkboxes.

[davidrhoderick]

First of all, the Frontity dependencies of this project are woefully out-of-date. That means that you can barely run this code as it is cloned from master without updating Frontity. Either that means the modifying instructions in the readme need to be updated to include a step about using npx npm-check-for-updates && npm install or it needs to be kept up-to-date so people can jump in and code changes.

Secondly, in needing checkboxes to work in CF7, I hacked together a solution for singular checkboxes to work. I too am busy and don't have time to flesh out the whole implementation at this very moment (maybe I'll give it a crack later on) but for now, this will allow a singular checkbox without default value to work in the Frontity site. It'll return either "yes" or "no" based on what is checked. It works for my usage and may help others at least get a functioning singular checkbox working, even it means multiple options won't work.