move test directory to be inside the docusign_esign directory

[juliocarrera]

This isn't really a bug. But when the docusign package is installed the test directory is placed at the same level as all the other site-packages in a Python installation. If other packages did the same thing and placed their test directories at the same level then I don't know what would happen but it's probably not good.

[mmallis87]

@juliocarrera good point. I created ticket DCM-2744 for us to look into removing test from the distribution, while keeping it in Github.