Add generic package download lwrp

Adds a lwrp to the cookbook which provides a generic method to retrieve artifacts from an artifactory server.  It is mostly intended for retrieving artifacts that do not have an already established method of retrieval (such as a zip or tar).  Artifacts such as java, node.js, ruby, and .Net packages would likely be better retrieved using appropriate maven/ivy, npm, gem and nuget/chocolatey resources instead of this lwrp.