$StorageContainerName may contains space

https://github.com/Azure/azure-quickstart-templates/blob/master/Deploy-AzTemplate.ps1

### Issue Details
Deploy-AzTemplate.ps1 contains next code:
```
[string] $ResourceGroupName = (Split-Path $ArtifactStagingDirectory -Leaf),
[switch] $UploadArtifacts,
[string] $StorageAccountName,
[string] $StorageContainerName = $ResourceGroupName.ToLowerInvariant() + '-stageartifacts',
```
If $ArtifactStagingDirectory contains one or more spaces deploy script will try to create a container with spaces that are not allowed by Azure and results in the following error:

### Repro steps
1. .\Deploy-AZTemplate.ps1 -ArtifactStagingDirectory '.\Azure Policies\VM Onboarding\' -UploadArtifacts -TemplateFile '.\Azure Policies\VM Onboarding\azuredeploy.json' -TemplateParametersFile '.\Azure Policies\VM Onboarding\newdev.parameters.json'
### Fix propose:
Adding .Replace(" ","-") in line 11
` [string] $StorageContainerName = $ResourceGroupName.ToLowerInvariant().Replace(" ","-") + '-stageartifacts',`

Open Deploy-AzTemplate.ps1 and inspect the $StorageContainerName default near the parameter declarations. Reproduce the issue with the supplied -ArtifactStagingDirectory command using spaces, then verify that deployment succeeds and the resulting storage container name complies with Azure naming rules.

Written by the indexing model from the issue text.