Throws errors when parsing invalid JSON

[refractalize]

I've actually replaced the implementation with the one found on node's stream documentation. Hope this doesn't hurt anybody's egos ;)

Importantly however, this makes the stream throw an error (via stream.on('error', ...)) if it meets a line in the input that isn't JSON (excluding whitespace only lines of course.)

We fix this by waiting for a \n before attempting to parse JSON, and finally by waiting for the end event to parse any remaining text (if the file doesn't end with \n.) The end event is the _flush() method on the Transform stream.

The module supports async and non-async modes, as before. (Although this needs some documentation... but I'm not really sure what situations you'd need one or the other.)

[refractalize]

@jcrugzz so you reckon this bit should do buffer concat, not string concat?