Windows: Fix hanging issue during cleanup

[aisouard]

Appveyor is failing after running the tests, this is certainly due to the changes over there: eb9ea40

[aisouard]

It's hanging again under OSX... https://travis-ci.org/aisouard/node-webrtc/jobs/216071123

[aisouard]

It comes from that line, https://github.com/aisouard/node-webrtc/blob/develop/src/globals.cc#L65

The current thread is set as the signaling one, but the signaling thread is used as the worker thread, I should pay more attention.

Testing under Windows before pushing again.

[aisouard]

The issue is way more complicated, it seems that Node is not really happy with ref counted objects.
Will be fixed tonight.

[aisouard]

Travis got stuck on that one, but it seems fixed.
Will reopen if it happens again.