[aws|storage] Return the object version in the request header and set an attribute value in the model.

lib/fog/aws/models/storage/file.rb

@@ -22,6 +22,7 @@ module Fog
         attribute :owner,               :aliases => 'Owner'
         attribute :storage_class,       :aliases => ['x-amz-storage-class', 'StorageClass']
         attribute :encryption,          :aliases => 'x-amz-server-side-encryption'
+        attribute :version,             :aliases => 'x-amz-version-id'
 
         def acl=(new_acl)
           valid_acls = ['private', 'public-read', 'public-read-write', 'authenticated-read']

lib/fog/aws/requests/storage/get_object.rb

@@ -96,6 +96,9 @@ module Fog
                     response.headers[key] = value
                   end
                 end
+
+                response.headers['x-amz-version-id'] = object['VersionId'] if bucket[:versioning]
+
                 unless block_given?
                   response.body = object[:body]
                 else