JavaScript services use less CPU

:Release Notes:
Fixed an issue that was causing JavaScript services to use up to 15% of the CPU when idle

:Detailed Notes:
The lifecycle handling of uv_poll_t objects in the nodejs-module-webos-sysbus add-on
was incorrect, and therefore the event loop was basically running constantly.

This *may* also address GF-13309, whoch was a crash caused by accessing freed
memory. The old code allowed some cases where the freed handle might be accessed later.

:Testing Performed:
Tested helloworld service. Idle CPU usage is ~0% now. In addition, with verbose logging
enabled, it's clear that the uv_poll_t objects are being allocated, started, stopped,
and deleted at the proper times.

:QA Notes:

:Issues Addressed:
[GF-12899] com.palm.service.accounts consuming 15% CPU at boot
[GF-13309] nodejs 0.10 crashing

Open-webOS-DCO-1.0-Signed-off-by: Mark Bessey <mark.bessey@lge.com>

Change-Id: Ibd6a0dba33926ee4d67b61c54dca57094578925b
Reviewed-on: https://g2g.palm.com/3097
Reviewed-by: Build Verification
Reviewed-by: Jason Lai <jason.lai@lge.com>
Tested-by: Jason Lai <jason.lai@lge.com>
Reviewed-by: Mark Bessey <mark.bessey@lge.com>
Tested-by: Mark Bessey <mark.bessey@lge.com>