Improve error message when using MSA with -Credential parameter

[cormacpayne]

Description

Fix for issue #3121

Previously, when a user tried to login with a Microsoft Account and the -Credential parameter, the following error would be thrown:

Login-AzureRmAccount: Sequence contains no elements

Now, a more meaningful error will be thrown in the same case:

Login-AzureRmAccount : -Credential parameter can only be used with Organization ID credentials. For more information,
please refer to http://go.microsoft.com/fwlink/?linkid=331007&clcid=0x409 for more information about the difference
between an organizational account and a Microsoft account.

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  …g the Credential parameter

[cormacpayne]

On demand: http://azuresdkci.cloudapp.net/view/1-AzurePowerShell/job/powershell-demand/1325/

[markcowl]

Tests? Please add a LiveOnly test for this scenario

[cormacpayne]

On demand: http://azuresdkci.cloudapp.net/view/1-AzurePowerShell/job/powershell-demand/1326/

[simeyla]

This still occurs with Connect-AzureRmAccount -TenantId $tenantid -Credential $cred after just updating AzureRM today. How come? Very confusing error.