Drush and other dev libraries (phpmd, phpunit) in composer.json.

[VeggieMeat]

Original issue: https://www.drupal.org/node/2648008

Why there are Drush, phpmd, etc and other dev module in this module's composer.json? Due to this, Composer Manager includes those tools too in global composer.json which is not always desired. For instance I've got certain version for Drush already installed globally in my Vagrant box - no need for another one.