Add JSON format option to find command

[filipiz]

I'm build a dmenu utility to save passwords, usernames or uris to clipboard.

In order to get useful values from resources I need a more reliable way to extract resources information other then awk on columnify output.

This new --json option will allow any utility tool parse the output and process it as needed.

[CLAassistant]

All committers have signed the CLA.

[almereyda]

Is there anything that would block the maintainers from merging here?

Are you able to request a review, to produce some attention on this PR?