Fixed compilation issue

Author: erwinvanhunen

Commands/Model/SPOTenant.cs

@@ -1,4 +1,5 @@
-using Microsoft.Online.SharePoint.TenantAdministration;
+#if !ONPREMISES
+using Microsoft.Online.SharePoint.TenantAdministration;
 using Microsoft.Online.SharePoint.TenantManagement;
 using Microsoft.SharePoint.Client;
 using System;
@@ -605,4 +606,5 @@ public SPOTenant(Tenant tenant)
 
         private bool disableCustomAppAuthentication;
     }
-}
+}
+#endif