Xamarin remote build target

<Target Name="RemoteBuild" DependsOnTargets="Build">
    <Message Text="Building with OSX server at $(MAC_SERVER_ADDRESS):$(MAC_SERVER_PORT) with BSAT '$(MAC_SERVER_BSAT)'." />
    <MSBuild
        Projects="project.csproj"
        Targets="_RemoteBuild"
        Properties="Configuration=$(Configuration);ServerAddress=$(MAC_SERVER_ADDRESS);HttpPort=$(MAC_SERVER_PORT);BSAT=$(MAC_SERVER_BSAT)" />
  </Target>