For #25116 - Renamed channel to be output for the Shotgun Write Node.
This change is backwards compatible to support either output or channel
keys in the templates.
Closes #4.
Merge branch 'master' of https://github.com/shotgunsoftware/tk-nuke-writenode

Conflicts:
	gizmos/WriteTank.gizmo
	info.yml
	python/tk_nuke_writenode/handler.py