Support templates for building the local filename

[whimboo]

Right now we use a hard-coded template to build the local filename. We should allow the user to define how the filename should be build.

[Nebelhom]

@whimboo

Is that what you roughly had in mind: Nebelhom@543611d

Please let me know, if I am going in the right direction. If it is, I will clean it up and right tests for it, as well, before I make a PR.

Thanks for looking at it :)

[whimboo]

Yeah. It looks nice and goes into the direction I want to see it. It gives customers the flexibility to name the download as what they want. Detailed integration feedback you will get via an upcoming PR. Thanks for taking the first step here Johannes!