change the volume_support default to False

With volume_support enabled, trove will require that new instances use
swift. It works fine without swift though and I suppose we want to avoid
an unneeded dependency on swift.
So if I remove this and leave only the proposal_dependencies changes, the proposal is always queued and never applied. I get this in the logs:

`W, [2014-07-22T14:23:46.846196 #14575]  WARN -- : Could not recover Chef Crowbar Data on load bc-swift-: #<Net::HTTPServerException: 404 "Not Found">`

which comes from these lines: https://github.com/crowbar/barclamp-crowbar/blob/e9b6737148494d6054d73ed5cec7ed3375099f6b/crowbar_framework/app/models/service_object.rb#L307-L310

`"inst" => role.default_attributes[@bc_name]["swift_instance"]` is `nil` and that's why there is a search for  `bc-swift-`