Test the package that would be released

[elmerbulthuis]

As discussed in #863 (comment)

We want to find and implement a way to test the final artifact just before they are released. This would be some form of e2e test. This would be the final test before releasing the package to the registry.

It has happend that people forget to update the files in the package.json, doing so would lead to a package that simple does not work, but current tests would pass. There are other errors possible in that area that could make a package seem ok when it really isn't.

This final release package is basically the artifact generated from npm pack, so this is the .tgz file. The test should be able to use this exact package in it's tests.

[elmerbulthuis]

I've been playing around with this concept a bit, and came up with the following:

https://github.com/LuvDaSun/test-npm-package

Needs some more extensive testing, but looks promising!