Make quiet mode optional on composer_project ops

It is difficult to troubleshoot package installation errors when
composer runs with the -q flag as all output including error messages is
suppressed.

This change adds an optional resource attribute to toggle 'quiet' mode
as required. It defaults to true for backwards compatibility.

Fixes #9
Merge pull request #11 from ingenerator/feat/quiet-mode-optional

Make quiet mode optional on composer_project operations