S3 bucket listing support and network code refactors.

* Adds support for listing all objects in an S3 bucket.
* Renames a bunch of network related classes (Download->Action)
* Net actions now have static constructors

logic/LegacyUpdate.h

@@ -19,7 +19,7 @@
 #include <QList>
 #include <QUrl>
 
-#include "net/DownloadJob.h"
+#include "net/NetJob.h"
 #include "tasks/Task.h"
 #include "BaseUpdate.h"
 
@@ -66,7 +66,7 @@ private:
 	QString lwjglTargetPath;
 	QString lwjglNativesPath;
 private:
-	DownloadJobPtr legacyDownloadJob;
+	NetJobPtr legacyDownloadJob;
 };