simplify test_nbextensions_configurator now that I've figure out how to set config values
simplify test_nbextensions_configurator now that I've figure out how to set config values

original-commit-id: 2e514782e33e4f41a3216b441060d9ff5476f8a1
original-commit-url: https://github.com/ipython-contrib/IPython-notebook-extensions/commit/2e514782e33e4f41a3216b441060d9ff5476f8a1

jcb91/jupyter_nbextensions_configurator,jcb91/jupyter_nbextensions_configurator,jcb91/jupyter_nbextensions_configurator,jcb91/jupyter_nbextensions_configurator