Please export _getTmpName

[joscha]

Hello there,

I am currently working on a module for node.js that runs an external process - this external process needs to get passed a file name to store its results in (until I read them from there and delete that file).
Currently I am using require('tmp').tmpdir and generate the file name myself, but your _getTmpName method does exactly this, so I would love to reuse it. Would it be possible to include it in the exports?

Cheers,
Joscha

[joscha]

See issue #5