JSON for Linking Data

[eamonnfaherty]

Hey ho!

Thanks for creating this awesome library!

I was wondering if you have any thoughts or plans on supporting json for linking data. It is used to power gmail actions (see https://developers.google.com/gmail/actions/actions/actions-overview) and it generally seems like a great thing to have anyway.

I do not mind spending the time doing the development work to get this in but was wondering if you would accept a PR if I do this. Also, is there any specific way it should be done?