fix: Cannot start the zookeeper client in a Node.js Worker thread

[deepcoldy]

Description

replace all uv_default_loop() by Nan::GetCurrentEventLoop()
here's GetCurrentEventLoop source code

Motivation and Context

Related to #281
The problem is uv_default_loop() return the main Node thread when program started, not the Worker's Event Loop in its isolated environment

How Has This Been Tested?

same as #281

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have read the code of conduct.
• I have read the contributing guide.
• I have updated the documentation accordingly (if applicable).

[DavidVujic]

This is great, thank you @deepcoldy!
I'll have a look and will try this out during the weekend.

[DavidVujic]

Starting zookeeper from a worker thread seems to work well with this change. 👏

I think it still is some work to make it work starting several instances in different worker threads, though. As an example, I still need to set the Ava test tool to not run in worker threads (in package.json).

But this change is a step in the right direction, and solves the issues described in #281

Nice job, thank you! 🚀

I will merge this one and build a new release within the next couple of days.