Implement parallel API requests for Socrata

[wrridgeway]

Let's see if we can use something like this to speed up the script.

[wrridgeway]

I spent a good chunk of the day trying to get this to work. requests-futures is simple to implement, but socrata's API throws a lot of errors while using it. resolving those errors slows things down to the point where there's really no performance gain:

{'content': {'code': 'conflict_operation',
             'error': True,
             'message': 'Another process is writing to the dataset; please try '
                        'again later'}}