Refactor how we download SDK packages. Fixes the problem where multiple license challenges cause downloads to fail.
Refactor how we download SDK packages. Fixes the problem where multiple
license challenges cause downloads to fail.

pivotal-sprout/sprout-osx-apps,wendorf/sprout-osx-apps,pivotal-sprout/sprout-osx-apps,wendorf/sprout-osx-apps,pivotal-sprout/sprout-osx-apps,wendorf/sprout-osx-apps