fix js tests:  * install @minrk's `scratchpad` nbextension before testing (it has a markdown readme to test rendering)  * check `window.list` rather than looking for body data attribute following change to template in ff2ad610c82b209801ee332374ddd231a6f0c60b
fix js tests:
 * install @minrk's `scratchpad` nbextension before testing (it has a markdown readme to test rendering)
 * check `window.list` rather than looking for body data attribute following change to template in ff2ad610c82b209801ee332374ddd231a6f0c60b

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