remove migrate tox environment, now that we have a nose test
remove migrate tox environment, now that we have a nose test

original-commit-id: 03fde46092fdd97f218bfe6118d25a97254c5fad
original-commit-url: https://github.com/ipython-contrib/IPython-notebook-extensions/commit/03fde46092fdd97f218bfe6118d25a97254c5fad

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