ACS - Download Data

[mdeland]

building on the script @abby-l published

• adds a scripts directory
• adds a few new imports, but I didn't add them to requirements.txt (since it wasn't core - but could!)
• moves state data into config
• moves full 2015 field list into a separate file, add a manual entered column to more succinctly describe contents (note, I didn't enter this for all 2K possible fields)
• make multiple requests per state if asking for many fields
• moves API key to an environment variable (didn't know if this was sensitive)

[dbolson]

Feel free to merge and we can review it post hoc. There's a build_the_list directory I had been using to put code in, and we can also update the readme with how to use it.

[mdeland]

sounds good