Make some calls asynchronous

[dcmeglio]

As more developers come on board all the HTTP traffic to load repositories will become a bottleneck. Some of these calls can be made asynchronous to allow multiple to occur at once.

[dcmeglio]

Probably going to delay this to 1.3.0 as it turns out to be a very large change. I will do it in two phases - 1 making the "checks" async (install repo pull, match up pull, update check). then 2 making the downloads associated with an install or update (pulling manifests and groovy files) async.