Add support for multiple iTunes providers.

[skos-ninja]

Currently if your iTunes account is linked to multiple developer accounts you get an error saying:
"Your Apple ID account is attached to other iTunes providers. You will need to specify which provider you intend to submit content to by using the -itc_provider command. Please contact us if you have questions or need help."

Which stops you being able to submit apps using that itunes account.

This was fixed in fastlane here: fastlane/fastlane#1524 but now requires an option in the interface to be able to pass this parameter.

[jeffyoung]

Thanks for reporting @skos-ninja. I'll mark this as an enhancement (to either ocnsidering adding that as a first class option on the task(s) or to provide an ability to add additional command line arguments freeform).

[madhurig]

For cases like this, I am adding a "fastlane arguments" input on the upload task: #80.

[madhurig]

We have added the ability to pass in additional fastlane arguments for advanced scenarios like this in version 1.126.0.

Thanks,
Madhuri