Change to year-over-year, add new datasets

This branch reverts back to the point where the data was year-over-year and adds some new datasets.

* Reverts building permits, code enforcement housing, and code enforcement nuisance to year-over-year
* Adds foreclosures, year-over-year
* Adds FOUR property value datasets. Aggregated property value (taxable value), aggregated property value (fair cash value), average property value (taxable value), average property value (fair cash value). We need to decide which one we want to use.
* Ensures that property value is formatted in dollars with commas and only two decimal places.
* For some reason, the slider disappeared.

**Remaining questions:**

* Which property value should we use?
* Where did the slider go, and can we convince it to come back?