add the package recipe to end all package recipes

This allows you to put <code>String</code>, <code>Array</code>, or hash-like Objects into an attribute, and install all packages found in that attribute. The rules are the following:

*  If there is a string, then install that package
*  If there is a <code>key,value</code> pair, install the package if the value evaluates to true (i.e <code>!!value</code> returns <code>true</code>
*  If the object is Enumerable, iterate on it.