Added script to convert Social Security data dumps to JSON
How to use:
1. Go to http://www.ssa.gov/oact/babynames/limits.html, download and unzip the dumps.
2. Convert to JSON with the following syntax: `node yob-to-json.js <filename> [threshold]`

Example output:
```shell
$ node yob-to-json.js yob2013.txt 10000
{"firstNames":{"male":["Noah","Liam","Jacob","Mason","William","Ethan","Michael","Alexander","Jayden","Daniel","Elijah","Aiden","James","Benjamin","Matthew","Jackson","Logan","David","Anthony","Joseph","Joshua","Andrew","Lucas","Gabriel","Samuel","Christopher","John","Dylan","Isaac"],"female":["Sophia","Emma","Olivia","Isabella","Ava","Mia","Emily","Abigail","Madison"]}}
```

`threshold` is the number of times the name must be used, so that it is included in the output.
The generated JSON data can directly be pasted into ChanceJS source.
Merge pull request #118 from oliversalzburg/feature/first-names

Added script to convert Social Security data dumps to JSON