Standardize volume

[j-t-t]

• Pulled all the ATR code except the propagating of volumes into the data_standardization section, as a standardize_volume script. Renamed ATR_utils to boston_volume because it's all boston-specific volume stuff
• Created a volume schema, storing the ATRs there instead of geocoded_atrs
• Changed the geocoding slightly so we're storing all addresses, from ATRs and TMCs in the geocoded_addresses.csv file. If the address exists, we read from that geocoded cache, otherwise we geocode, add to the cache and write out the cache to geocoded_addresses at the end
• Pulled the propagate volume functionality into its own script, called propagate_volume, and hooked that up into the pipeline
• Made this compatible with existing TMC functionality. Pulling parsing TMCs into the new schema in the data_standardization step will be a later task
• Added some tests so code coverage at least doesn't go down. Having code coverage actually go up will also be a later task

[terryf82]

@j-t-t these are only minor suggestions and functionally I can't see any reason why this can't be merged.

@andhint do you have any feedback regarding the changes to ATR handling?