Update DotNetInstallerUri to https://dot.net/v1/dotnet-install.ps1

[tsomersu]

Currently the cake/build.ps1 has the following reference for dotnet install script:

$DotNetChannel = "preview";
$DotNetVersion = "1.0.0-preview2-003121";
$DotNetInstallerUri = "https://raw.githubusercontent.com/dotnet/cli/rel/1.0.0-preview2/scripts/obtain/dotnet-install.ps1";

Now that it is out of preview, these could be updated to:

$DotNetChannel = "production";
$DotNetVersion = "Latest";
$DotNetInstallerUri = "https://dot.net/v1/dotnet-install.ps1"

See #https://github.com/dotnet/cli/issues/5773#issuecomment-285160511

[devlead]

Yes that's on our todo, need to update Cake itself to utilize new SDK, likely v0.20.0 timeframe maybe sooner.