Enabling readable stream

I used this for a project where I needed export a huge about of data to CSV. The buffered code from before caused the process to run out of memory. Now presenting: readable. I'm kind of a n00b with JS Node streams, but this is the first round.  Post issues if anything comes up! 

```
//pipe to console
jsoncsv.createReadStream({data : [...], fields : [...]}).pipe(process.stdout)
```

pipe to file
```
var fs = require("fs")
var writable_file = fs.createWriteStream("output.csv", {encoding : 'utf8'})
jsoncsv.createReadStream({data : [...], fields : [...]}).pipe(writable_file)
```

You can also use the standard readable stream events like: 'end', 'readable' to detect the end of the stream or read it yourself. 
```
var reader = jsoncsv.createReadStream({data : [...], fields : [...]})
reader.on('end', function() { /* triggers when the reader has nothing left to read; when done*/ })
reader.pipe(process.stdout) // go ahead and pipe it somewhere
```