debian packaging: support for multiple control files missing

[fbatschi]

When using the release tool for packaging of debian deb files you need to provide a control file.
When you have multiple deb-config targets defined they would all take the same control file at .release/debian/control - there is no way to define the control file to use.

[dreadwarrior]

I'd like to tackle this issue.

First, I started to write some tests for the method_deb module.

Before proceeding, I'd like to ask if you can perform a code review. I'm not that much experienced in shell script (unit) testing. ;) I did a lot of stubbing / mocking, don't know if this is the right approach.

This is the current state of the method_deb test suite:

https://github.com/dreadwarrior/release/blob/feature.deb-multiple/test/method_deb_test.sh

Thanks :)