Write a unit test for pulling data from JSON

[tomschenkjr]

Need to ensure that posixify() worked both with csv and json files. Right now we're only testing CSV files.

[nicklucius]

Looks like posixify() expects dates in a different format than Socrata uses for JSON files.

Here are the two formats posixify() expects:

## Define regex patterns for short and long date formats, which are the two 
## formats that are supplied by Socrata. 
patternShort <- paste0("^[[:digit:]]{1,2}/[[:digit:]]{1,2}/[[:digit:]]{4}$")
patternLong <- paste0("^[[:digit:]]{1,2}/[[:digit:]]{1,2}/[[:digit:]]{4}","[[:digit:]]{1,2}:[[:digit:]]{1,2}:[[:digit:]]{1,2}","AM|PM","$")

Here's an example of patternLong: "09/14/2012 10:38:01 PM"

But the Socrata JSON download uses ISO 8601 dates like this: "2014-10-13T00:00:00.000"

https://dev.socrata.com/docs/datatypes/floating_timestamp.html#,