Support directories as input for 'object' field

[Qworel97]

Had problem that I couldn`t use your tool to generate schema from 2500+ files. Command line looked like 'genson * > res.json'. That leads to '/bin/rm: cannot execute [Argument list too long]'. It would be nice if 'object' supported directory input. I already forked your project and supported it for 'object', will do that for 'schema' parameter'. That will make tool more user-friendly. Can create pull request with these changes.

[wolverdude]

Please do submit the PR. I'd love to see it.