Update dockerfile to pull in dotnet image from mcr (#235)

* Update dockerfile to pull in dotnet image from mcr

Update dockerfile to pull in dotnet image from mcr.microsoft.com

* Update Dockerfile

DeploymentCloud/Deployment.Kubernetes/Dockerfile

@@ -1,4 +1,4 @@
-FROM microsoft/dotnet:2.2-aspnetcore-runtime
+FROM mcr.microsoft.com/dotnet/aspnet:3.1
 WORKDIR /app/aspnetcore
 EXPOSE 5000
 ARG servicetarname

DeploymentLocal/Dockerfile

@@ -1,8 +1,8 @@
-FROM microsoft/dotnet:2.2-sdk AS build-env
+FROM mcr.microsoft.com/dotnet/sdk:3.1 AS build-env
 
 WORKDIR /app/aspnetcore
 
-FROM microsoft/dotnet:2.2-aspnetcore-runtime
+FROM mcr.microsoft.com/dotnet/aspnet:3.1
 
 WORKDIR /app/aspnetcore
 
@@ -57,4 +57,4 @@ EXPOSE 2020
 
 # Adding the execute permission. 
 RUN chmod +x ./finalrun.sh
-ENTRYPOINT ["finalrun.sh"]
+ENTRYPOINT ["finalrun.sh"]