Revert "Revert "Don't output to stdout from lib non-interactive methods""

This reverts commit b33d4bc2f1d26ee3526b9d7f530f468a9d5b5a5e.
fix system silent call
Merge branch 'fix_system_call' into 'master'

Fix system_silent call

Origin request has been provided by our contributor @cirosantilli. We had to revert it and rework.

origin commit - https://dev.gitlab.org/gitlab/gitlabhq/commit/0b1084a4538bc46684c8620410988d3b1093e7ab

See merge request !1243