Add --debug option to show JSON responses

[phatblat]

Is your feature request related to a problem? Please describe.

Related to problems like #311 which can happen when the iTunes Search API returns unexpected JSON.

Describe the solution you'd like

I'd like a way to be able to print/dump the response JSON (and maybe HTTP headers) so that the data can be reviewed when errors occur.

Describe alternatives you've considered

Currently, the only way to view the JSON is to debug the project in Xcode or use a REST client with a problem search. Some of these issues are transient so this feature would allow mas users to easily collect this data for bug reports.

[andrewcrook]

+1

That would be useful.