Enable comments in taglibs

[iox]

I modified the permissions in owned_model.rb so new records are taken into account.

After that, I also had to modify the form a bit:

• Remove the user select and make a hidden-field with its id
• Modify the action URL so it uses the id of the taglib. I think this has to do with the customised URLs in the taglibs (without ID).

And now it works :)