Add URL for dotnet-cli RC builds
Add URL for dotnet-cli RC builds

For example:

https://dotnetcli.azureedge.net/dotnet/Sdk/1.0.0-rc4-004771/dotnet-dev-osx-x64.1.0.0-rc4-004771.pkg
https://dotnetcli.azureedge.net/dotnet/Sdk/1.0.0-rc4-004915/dotnet-dev-osx-x64.1.0.0-rc4-004915.pkg

are valid URLs for RC builds, and for preview the existing format works:

https://dotnetcli.azureedge.net/dotnet/preview/Installers/1.0.0-preview2-1-003177/dotnet-dev-osx-x64.1.0.0-preview2-1-003177.pkg

kevmoo/travis-build,andyli/travis-build,JuliaCI/travis-build,andyli/travis-build,JuliaCI/travis-build,craigcitro/travis-build,craigcitro/travis-build,kevmoo/travis-build