Update radar scan and warning backends to give more status/progress information

[jthielen]

In 2018, we didn't know directly how many radar scans were remaining in the simulation. This would be good information to have while the simulation is running.

Applicable files:

• https://github.com/isuams/chase_simulation/blob/master/backend_scripts/simulation_radar.py
• https://github.com/isuams/chase_simulation/blob/master/backend_scripts/simulation_warning.py