Implement modeling API

[jameshadfield]

Currently the viz uses 2 (committed) modelling CSVs from the simulated data repo. As such, it only works for H3N2 or H1N1 with geo resolution set to neighborhood. This must be replaced with a call to the actual server API.

Note that the API implemented between the client and the server is roughly along the lines of what was discussed in slack, but is overly simplified and incomplete.

[kairstenfay]

Connect IDM model output to viz prototype

[kairstenfay]

The necessary work here has been started in the branch connect_to_modeling_api.