config.go:
Removed all of the windows-specific net/url hackery since it's now handled mostly by download.go
Removed the replacement of '\' with '/' since url.Parse does it now.
Added knowledge of the other protocols implemented in download.go (ftp, smb)
Removed some modules that were unused in this commit.
download.go:
Moved the file-path conversions for the different protocols into their own internally callable functions.
Shuffled some of the functions around in case someone wants to implement the ability to resume.
Modified DownloadClient.Get to remove the CopyFile special case and trust the protocol implementations if a user doesn't want to copy the file.
Since all the protocols except for HTTPDownloader implement Cancel, added a Resume method as a placeholder for another developer to implement.
Added a few missing names from their function definitions.
Fixed the syntax in a few lines due to my suckage at go.
Adjusted the types for progress and total so that they support 64-bit sizes.
Removed the usage of the bufio library since it wasn't really being used.
Added proper support for validating a downloadableURL containing a UNC or relative uri.
Removed the workaround for an earlier Go issue that had remained dormant in common/download.go (issue #5927).
When building a .vmx file via the vmware-iso builder, transform the path to the correct os-formatted one (using filepath.FromSlash).