tools: re-enable comma-spacing linter rule

tools: re-enable comma-spacing linter rule

The rule was disabled because of an eslint bug which is now resolved.
All code in lib was already conforming and only test code needed a few
changes to make the linter happy with this rule enabled.

Ref: https://github.com/eslint/eslint/issues/2408

PR-URL: https://github.com/nodejs/io.js/pull/2072
Reviewed-By: Yosuke Furukawa <yosuke.furukawa@gmail.com>
Reviewed-by: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Alex Kocharin <alex@kocharin.ru>