Jupyter-packaging

- Add more options to Build [84](https://github.com/jupyter/jupyter-packaging/pull/84) ([jtpio](https://github.com/jtpio))

* Clean up handling of version info [82](https://github.com/jupyter/jupyter-packaging/pull/82) ([jtpio](https://github.com/jtpio))

* Do not run ensure_targets in develop mode [79](https://github.com/jupyter/jupyter-packaging/pull/79) ([jtpio](https://github.com/jtpio))

* Add ability to ensure targets [77](https://github.com/jupyter/jupyter-packaging/pull/77) ([jtpio](https://github.com/jtpio))
* Add version info helper function [76](https://github.com/jupyter/jupyter-packaging/pull/76) ([afshin](https://github.com/afshin))

* Fixes handling of backend [75](https://github.com/jupyter/jupyter-packaging/pull/75) ([jtpio](https://github.com/jtpio))

* Fix invalid command build [72](https://github.com/jupyter/jupyter-packaging/pull/72) ([xmnlab](https://github.com/xmnlab))