readCSV returns wrong dtypes

in browser, readCSV from 
https://github.com/codeforamerica/ohana-api/blob/master/data/sample-csv/contacts.csv

the dtypes are

```
[
    "int32",
    "int32",
    "float32",
    "float32",
    "string",
    "string",
    "float32",
    "float32"
]
```

but last two should be string