Use Nan2 API to be compatible with all node versions

[Infernoman]

This is in reference to PR #5 Just creating a new issue, since the PR is not quite ready. Issues are now enabled on node-multi-hashing.

[Kukunin]

Isn't UNOMP project abandoned?

I can prepare another PR about Nan2 and newest node support, but I need testing. It seems, that neoscrypt problem is related to only neoscrypt, but I didn't try anything except scrypt.

Are you interested in that?

[Kukunin]

Another question, that if node-multi-hashing works fine with the newest node, there are still may be regressions in both stratum-pool and nomp itself.

[Kukunin]

btw neoscrypt crashes even on latest UNOMP master because of this commit: dc943d3 - it enables -Ofast which causes segmentation faults

[krisklosterman]

https://github.com/krisklosterman/node-multi-hashing

Needs testing and some work on scrypt-jane