[ENH] add inline exercises

[ljwolf]

This is done partially in geopandas/scipy2018-geospatial-data#15, but we need to be more proactive about including this in our material.

Two examples of how this is done are provided in the scipy18 branch, the case-conflict-mapping.ipynb and case-gini-in-a-bottle.ipynb files.

[ljwolf]

For what it's worth, when asked, participants generally preferred the lecturing/demonstration than the material in person.

However, not sure if this was a fluke.

[ljwolf]

this will include incorporating geopandas/scipy2018-geospatial-data#15