Error in RDS farm deployment using existing active directory when having - in Resource Group

RDS farm deployment using existing active directory - https://github.com/Azure/azure-quickstart-templates/tree/master/rds-deployment-existing-ad

### Issue Details
During the deployment of the "RDS farm deployment using existing active directory" code in Azure I noticed that when I use a '-' or a upper-case characters in the Resource Group name I'll get the error that the validation is failed.

Details shows:
"The domain name label [name] is invalid. It must conform to the following regular expression: ^[a-z][a-z0-9-]{1,61}[a-z0-9]$. (Code: InvalidDomainNameLabel)"

This is related to:
`
"gwdnsLabelPrefix": "[concat('gwd', resourceGroup().name)]",
"cbdnsLabelPrefix": "[concat('cbd', resourceGroup().name)]",
`

After fixing this I could continue with the deployment. However it fails again, this time about an invalid parameter about the storage:
https://*.blob.core.windows.net/sac*-*/rdsh-1-os-disk.vhd is invalid. Container names must be 3-63 characters in length and may contain only lower-case alphanumeric characters and hyphen. Hyphen must be preceeded and followed by an alphanumeric character."

Start with the rds-deployment-existing-ad template and inspect the gwdnsLabelPrefix and cbdnsLabelPrefix expressions named in the report. Then trace how the storage URL and container name are formed. Done means deployments using resource group names with hyphens or uppercase characters produce valid DNS labels and storage container names without the reported validation errors.

Written by the indexing model from the issue text.