Deploy-AzureResourceGroup.ps1 fails to upload artifacts with new cmdlets

Script: Deploy-AzureResourceGroup.ps1

### Issue Details
New version 3.0.0 of AzureRm have changed output of ```Get-AzureRmContext``` now it returns subscription id as ```(Get-AzureRmContext).Subscription.Id``` instead of ```(Get-AzureRmContext).Subscription.SubscriptionId``` in earlier versions.

this produces error when using -UploadArtifacts switch

I believe code need to be changed so it can handle both newer and older versions of cmdlets, for example, change from:
```
# Create a storage account name if none was provided
if($StorageAccountName -eq "") {
$subscriptionId = ((Get-AzureRmContext).Subscription.SubscriptionId).Replace('-', '').substring(0, 19)
$StorageAccountName = "stage$subscriptionId"
}
```
to something like
```
# Create a storage account name if none was provided
if($StorageAccountName -eq "") {
if ((get-command get-azurermcontext).version -ge "3.0")
{
$subscriptionId = ((Get-AzureRmContext).Subscription.Id).Replace('-', '').substring(0, 19)
}
else
{
$subscriptionId = ((Get-AzureRmContext).Subscription.SubscriptionId).Replace('-', '').substring(0, 19)
}
$StorageAccountName = "stage$subscriptionId"
}
```

Start in Deploy-AzureResourceGroup.ps1 and inspect the storage-account naming path used with the -UploadArtifacts switch. Check how Get-AzureRmContext exposes the subscription identifier in the older and newer cmdlet versions. Done means artifact upload works and the generated storage account name is correct with both versions.

Written by the indexing model from the issue text.