Allow updates from secure locations

In the near future we will have a need to store items coming through Studio's update system in secure locations, ones requiring some sort of authentication to download. Specifically this is planned for the Mobware (AMW) project.

Ideally this will likely involve Studio querying for a list of updates, getting the listing, finding the URL for an update (all as usual so far), then hitting that URL with the user's Appcelerator login credentials through Studio's APIs in order to pull down the secured download. Same exact process, just passing credentials with the actual download request.