Add base object NetoworkMessageDelivery for API entity SoftLayer_Network_Message_Delivery
user
```ruby
#--
# Copyright (c) 2014 SoftLayer Technologies, Inc. All rights reserved.
#
# For licensing information see the LICENSE.md file in the project root.
#++

module SoftLayer
  ##
  # Each SoftLayer NetworkMessageDelivery instance provides information about
  # the username/password combination for a specific Network Message Delivery
  # account.
  #
  # This class roughly corresponds to the entity SoftLayer_Network_Message_Delivery
  # in the API.
  #
  class NetworkMessageDelivery < ModelBase
    include ::SoftLayer::DynamicAttribute

    ##
    # :attr_reader:
    # The date this username/password pair was created.
    sl_attr :created,  'createDate'

    ##
    # :attr_reader:
    # The date of the last modification to this username/password pair.
    sl_attr :modified, 'modifyDate'

    ##
    # :attr_reader:
    # The password part of the username/password pair.
    sl_attr :password

    ##
    # :attr_reader:
    # The username part of the username/password pair.
    sl_attr :username

    ##
    # The message delivery type description of a network message delivery account.
    sl_dynamic_attr :description do |resource|
      resource.should_update? do
        #only retrieved once per instance
        @description == nil
      end

      resource.to_update do
        description = self.service.object_mask("mask[type.description]").getObject['type']
        description['description']
      end
    end

    ##
    # The message delivery type name of a network message delivery account.
    sl_dynamic_attr :name do |resource|
      resource.should_update? do
        #only retrieved once per instance
        @name == nil
      end

      resource.to_update do
        name = self.service.object_mask("mask[type.name]").getObject['type']
        name['name']
      end
    end

    ##
    # The vendor name for a network message delivery account.
    sl_dynamic_attr :vendor do |resource|
      resource.should_update? do
        #only retrieved once per instance
        @vendor == nil
      end

      resource.to_update do
        vendor = self.service.object_mask("mask[vendor.name]").getObject['vendor']
        vendor['name']
      end
    end

    ##
    # Returns the service for interacting with the network message delivery instance
    # through the network API
    #
    def service
      softlayer_client[:Network_Message_Delivery].object_with_id(self.id)
    end

    protected

    def self.default_object_mask(root)
      "#{root}[createDate,id,modifyDate,password,username,type[description,name],vendor.name]"
    end
  end
end #SoftLayer
```
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