Revision 1063026

Only make available/access drivers within a request

There is no point talking about a driver outside the context of a request
anymore, since we don't know until request time what driver the user wants.

Because of the lazy instantiation of drivers, accessing a driver outside of
a request can lead to nasty races.

  * lib/drivers.rb: do not include module Deltacloud in Object
  * lib/deltacloud/helpers/application_helper.rb: include module Deltacloud