Print nothing when used with quiet option

[mnishiguchi]

This is a preparation for PR #157

This pull request allows users to optionally suppress help text that gets printed by default.

Changes

• Wrap the printing logic in unless unquote(opts[:quiet]) do ... end, without changing the logic

[fhunleth]

Between removing path completion and combining all beam files into one large one, import Toolshed is now possible and it doesn't print anything.