Refactor File#== to avoid an unnecessary API call

The new_record? call used to cause an API call to fedora, which we are
now able to avoid.

lib/active_fedora/file.rb

@@ -51,8 +51,10 @@ def initialize(parent_or_url_or_hash = nil, path=nil, options={})
     end
 
     def ==(comparison_object)
-      return true if comparison_object.equal?(self)
-      comparison_object.instance_of?(self.class) && comparison_object.uri == uri && !comparison_object.new_record?
+      super ||
+        comparison_object.instance_of?(self.class) &&
+        id.present? &&
+        comparison_object.uri == uri
     end
 
     def ldp_source