Jupyter-packaging

* Fix Usage of install_npm [71](https://github.com/jupyter/jupyter-packaging/pull/71) ([afshin](https://github.com/afshin))

* Proposal: Improved integration with setuptools [69](https://github.com/jupyter/jupyter-packaging/pull/69) ([afshin](https://github.com/afshin))
* Update changelog [68](https://github.com/jupyter/jupyter-packaging/pull/68) ([blink1073](https://github.com/blink1073))

* Use sdist from setuptools not distutils [66](https://github.com/jupyter/jupyter-packaging/pull/66) ([astrofrog](https://github.com/astrofrog))

* Fix packagedata docstring examples [62](https://github.com/jupyter/jupyter-packaging/pull/62) ([vidartf](https://github.com/vidartf))

* Only run build command if one is given [61](https://github.com/jupyter/jupyter-packaging/pull/61) ([vidartf](https://github.com/vidartf))
* Add basic test for skip_if_exists [60](https://github.com/jupyter/jupyter-packaging/pull/60) ([jtpio](https://github.com/jtpio))

* Fix typo in skip_if_exists [59](https://github.com/jupyter/jupyter-packaging/pull/59) ([jtpio](https://github.com/jtpio))