Support ZF2.3.2

[lolletsoc]

Hey @jstaerk,

Would we be able to get a new release? Please let me know if there's anything I can help you with.

Thank you!

[jstaerk]

What do you need the new version for? In particular #435 could use some more testing, it could happen that zugferdimporter fails, you could add tests if you like (e.g. there are a couple of zugferdinvoiceimporter tests where one could also add zugferdimporter).
The development documentation tells you how you can declare a "version" to be used by gradle or maven as new test version.

[jstaerk]

recycling this issue to support the new zugferd version, trying to release next week