Config Options around Ordercloud Environments.

[oliverheywood451]

It would be nice to have config options around the three different environments. So that a new instance of OrdercloudClient could be created something like this

new OrderCloudClient(new OrderCloudClientConfig()
			{
				GrantType = GrantType.ClientCredentials,
                                Enviornment = OrderCloudEnvironment.Staging,
				ClientId = clientID,
				Roles =  new ApiRole[] { }
			});