Fix #1846 as well as some other help text issues including: Get-AzureServiceRemoteDesktopExtension, Get-AzureServiceDiagnosticsExtension, Remove-AzureServiceRemoteDesktopExtension, Remove-AzureServiceDiagnosticsExtension, etc.

@DanGarvey Could you please help verify? Thanks.
Merge branch 'dev' of https://github.com/AzureRT/azure-sdk-tools into dev
Merge pull request #57 from huangpf/dev

Fix #1846 as well as some other help text issues including: Get-AzureSer...