Updated ReadMe to include multiple server polling documentation

Fixing PowerShell bug with k8sworker image docker file and reordering…

… the build file to build the full worker very last.

Updating the Azure PowerShell version to 4.7

Updating the Azure PowerShell version to 4.7

Added .NET Core, NodeJS, and Java worker images

Fixing the .net core sdk not found issue

Updating the base docker image to not have the docker in docker featu…

…re enabled

Minor read me update to make it clearer.