Object URLs in the sitesFile

This adds functionality to the project to allow URLs to specify a source URL along with a file name that the source document will be renamed to.  I cam across an issue where two different datasets had the same name and this was my solution.  Additionally if you specify a second argument to the object for a zip file, the code will assume that you want to unzip the source zip into the specified directory name.  Take a look at the MaxMind downloads for an example.  The object must have a valid URL as well as a valid file name. 

Additionally I added a public export so that this may be included as a module.