Updates package to use tools from newer cookiecutter

[JasonWeill]

Updates files in this package to use the newer cookiecutter per @fcollonval in #43. Now, with jupyter-packaging installed, the jupyter labextension develop . --overwrite completes without errors. (If you don't have that package installed, the script will prompt you to install it.)

[fcollonval]

Thanks a lot @jweill-aws

If you don't have that package installed, the script will prompt you to install it.

Actually if you don't have jupyter-packaging, it does not matter when running jupyter labextension develop . --overwrite. The trouble comes from the need to get the python package name when executing jupyter labextension develop. Hence the new setup.py allows to get it without the need for jupyter-packaging. But the latter is still used by pip in the virtual build environment.