When 'create public IP address' is enabled, 'name prefix' must be lowercase

[matt-richardson]

As vmName is used for the domain label, it must be lowercase. Having an upper case/mixed case name results in an error:

[2016-09-09 09:51:21,533]   WARN [sion=2015-11-01] - ouds.azure.arm.AzureCloudImage - Failed to create deployment in resource group TCWIN2016-22: 400 is not a valid polling status code
The domain name label TCWIN2016-22 is invalid. It must conform to the following regular expression: ^[a-z][a-z0-9-]{1,61}[a-z0-9]$. 
jetbrains.buildServer.clouds.CloudException: Failed to create deployment in resource group TCWIN2016-22: 400 is not a valid polling status code
The domain name label TCWIN2016-22 is invalid. It must conform to the following regular expression: ^[a-z][a-z0-9-]{1,61}[a-z0-9]$.
    at jetbrains.buildServer.clouds.azure.arm.connector.AzureApiConnectorImpl$17.failure(AzureApiConnectorImpl.java:639)
    at com.microsoft.azure.AzureClient.getPutOrPatchResultAsync(AzureClient.java:193)
    at com.microsoft.azure.management.resources.DeploymentsOperationsImpl$10.onResponse(DeploymentsOperationsImpl.java:410)
    at retrofit2.OkHttpCall$1.callSuccess(OkHttpCall.java:135)
    at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:114)
    at okhttp3.RealCall$AsyncCall.execute(RealCall.java:133)
    at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: com.microsoft.azure.CloudException: 400 is not a valid polling status code: The template deployment 'TCWIN2016-22' is not valid according to the validation procedure. The tracking id is '84868b2a-b540-4698-a4b8-c0d8c1ff78d9'. See inner errors for details. Please see https://aka.ms/arm-deploy for usage details.
    at com.microsoft.azure.AzureClient.getPutOrPatchResultAsync(AzureClient.java:185)
    ... 8 more