Jupyter-dashboards

* Fix code cell overflow in layout mode
* Fix scroll bars that appear within cells of a certain size
* Fix hidden cells from being cut-off in layout mode
* Fix failure to load extension JS in certain situations
* Fix meetup streaming demo filter box
* Update to Gridstack 0.2.4 to remove a workaround

* Fix gridstack break with lodash>=4.0
* Remove notebook 4.1 cell focus highlight in dashboard preview
* Hide stderr and errors in dashboard preview, send them to the browser console

* Separate `pip install` from `jupyter dashboards [install | activate | deactivate]`
* Match the Python package to the distribution name, `jupyter_dashboards`
* Fix cell overlap when one cell has the minimum height
* Prevent stderr and exception messages from displaying in dashboard modes
* Update demo notebooks to stop using deprecated `UrthData.setItem` from declarative widgets.

* Make compatible with Jupyter Notebook 4.1.x
* Remove all download and deployment related backend code in. Refer users to the separate `jupyter_cms` and `jupyter_dashboards_bundlers` packages for these features.
* Keep compatible with Jupyter Notebook 4.0.x

* Revert to old jupyter\_notebook\_server.py config hack to remain compatible with jupyter\_declarativewidgets and jupyter\_cms (until they change too)

* Fix errors on install when profiles don't exist
* Fix styling leaking out of dashboard mode