Add file extension to custom path part

[SiggiSmara]

First, thanks for your effort in creating this project! I had halfway started something similar on my own some time ago and abandoned it due to time constraints. What you have done here is way more advanced than what I had accomplished before giving up.

The pull request addresses #271 at least the extension part. I wasn't interested in going further than that but I also felt sad that this IMHO very useful enhancement didn't result in a pull request at the end of it so here it is.

I can also verify that it works as indicated.

EDIT: Btw, I'm more than happy adding a test for this but I wasn't sure if/where/how you are testing for such things. If you point me in the right direction then I can add that to the pull request.

[CLAassistant]

All committers have signed the CLA.

[jmathai]

Thanks for the PR. Looks good to me. Before merging it would be great to have a unit test that verifies this functionality so we don't break it in the future.

Let me know if that's not something you feel comfortable doing.

[SiggiSmara]

Sorry for the late reply. I'm more than happy to add some unit test for it. Can you point me to the file that does the test for the other parameters in that function? I think it would make sense to have them all in one place, but I don't know the code base well enough.

[jmathai]

Thanks. Here is an example.