Intended fix for Issue #216 - Changed url creation to simply join strings

As path.join produces backslashes on windows need an alternative to not have broken links when built on my machine.

I cannot run your tests for some reason so cannot guarantee this hasn't broken everything. I would also want to check there is nowhere else that this issue is also occurring. Not sure if the https is correct!

I thought would submit a pull request to highlight where the issue is occurring for me and to allow you to take a look.