change the way validators use messages

for example if I use:

<message key="user.name.errors.required"></message>

and the key doesnt exist ill just get blank error, I know i
could put a message in there myself to display if the key is
not valid but can we change it so that if the message is
blank like it is now it just displays 'user.name.errors.required'?

this would be consistent with the way getText() works.. just
displaying the key if the message is not present.

so if theres a message for the key use that, if theres a message (and bad key) use the message, if theres no message and key is provided return the key.