title: spree: Missing required parameter :login
body: <p>I've just inherited a spree project that has an issue. On checkout, after the user provides their credit card information, the system has a rails exception. I'm looking for guidance on what might be requiring the login parameter.  I'm quickly learning how spree works, so any guidance is helpful. Thanks!</p>
  
  <pre><code>Started PUT "/checkout/update/payment" for 107.3.138.229 at 2012-09-28 08:52:11 -0700
  Processing by Spree::CheckoutController#update as HTML
    Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"XXXXXXX=", "order"=&gt;{"payments_attributes"=&gt;[{"payment_method_id"=&gt;"2"}], "coupon_code"=&gt;""}, "payment_source"=&gt;{"2"=&gt;{"number"=&gt;"[FILTERED]", "month"=&gt;"X", "year"=&gt;"XXXX", "verification_value"=&gt;"XXX", "first_name"=&gt;"XXX", "last_name"=&gt;"XXX"}}, "commit"=&gt;"Save and Continue", "state"=&gt;"payment"}
  Completed 500 Internal Server Error in 464ms
  
  ArgumentError (Missing required parameter: login):
    active_utils (1.0.4) lib/active_utils/common/requires_parameters.rb:11:in `block in requires!'
    active_utils (1.0.4) lib/active_utils/common/requires_parameters.rb:4:in `each'
    active_utils (1.0.4) lib/active_utils/common/requires_parameters.rb:4:in `requires!'
    activemerchant (1.20.4) lib/active_merchant/billing/gateways/authorize_net.rb:74:in `initialize'
    spree_core (1.1.3) app/models/spree/gateway.rb:25:in `new'
    spree_core (1.1.3) app/models/spree/gateway.rb:25:in `provider'
    spree_core (1.1.3) lib/spree/core/delegate_belongs_to.rb:82:in `delegator_for'
    spree_core (1.1.3) lib/spree/core/delegate_belongs_to.rb:44:in `block (2 levels) in delegate_belongs_to'
    spree_core (1.1.3) app/models/spree/payment/processing.rb:128:in `block in gateway_action'
    spree_core (1.1.3) app/models/spree/payment/processing.rb:172:in `protect_from_connection_error'
    spree_core (1.1.3) app/models/spree/payment/processing.rb:125:in `gateway_action'
    spree_core (1.1.3) app/models/spree/payment/processing.rb:22:in `authorize!'
    spree_core (1.1.3) app/models/spree/payment/processing.rb:11:in `process!'
    activerecord (3.2.8) lib/active_record/associations/collection_proxy.rb:89:in `each'
    activerecord (3.2.8) lib/active_record/associations/collection_proxy.rb:89:in `method_missing'
    spree_core (1.1.3) app/models/spree/order.rb:380:in `process_payments!'
    spree_core (1.1.3) app/models/spree/order.rb:83:in `block (2 levels) in &lt;class:Order&gt;'
  </code></pre>