rm \Command::_clear_args

This method is now protected on \Oil\Command class.

> Compile Error - Access level to Command::_clear_args() must be protected (as in class Oil\Command) or weaker in .../novius-os/framework/classes/fuel/oil/command.php
Merge pull request #75 from jguyomard/patch-4

Remove method extended \Command::_clear_args