Fix a crash in node.js services

:Release Notes:
Fixed a crash in nodejs-webos-sysbus related to fd watcher handling

:Detailed Notes:
One last fix in the fd watcher handling - need to call uv_close after calling uv_poll_stop, and free memory from there.

:Testing Performed:
Tested multiple service requests (subscriptions from two sessions), which triggered the error pretty frequently.

:QA Notes:

:Issues Addressed:
[GF-27852] Crash in node.js, possibly related to unregistering handles

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

Change-Id: Ia120ac1edf266a9b16543ccf5c3f3de6e81441c5
Reviewed-on: https://g2g.palm.com/3314
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>