Json output mode

[lack]

I've just started using the tool, but keep finding weird corner cases in my personal workflow that I'd like to automate.

For this reason I'd love for the tool to generically support a --json flag which goes one step lower than the --plain to produce machine-readable json output.

I'm sure I could talk to the actual rest api myself, but this tool is so convenient for wrapping a bunch of ugly things so I don't have to worry about them, and it would be a powerful feature to open up the tool to script integration.

[php-coder]

See #256

[ankitpokhrel]

The upcoming release will include --raw for JSON output and additionally --csv for CSV output.