curl: follow redirects and silent for kvminstall

Signed-off-by: Ahmet Alp Balkan <ahmetb@microsoft.com>
Merge pull request #16 from ahmetalpbalkan/curl

curl: follow redirects and silent for kvminstall
Add Dockerfile which gets the latest nightly build of ASP.NET 5
Merge pull request #20 from vlesierse/nightly

Added Dockerfile to download the nightly build of ASP.NET 5