[html-formfu] Model::HashRef and Repeatables without nested_name

[Mario Minati]

During my work on rewriting the Repeatable element for an easier client side 
javascript handling I found out that Model::HashRef cannot handle Repeatable 
elements without nested_name.

The function get_repeatable just ignores them.

To save users from running to that problem I changed the code of 
FF::Model::HashRef to die if there is a Repeatable without name (rev. 1509).


Greets,

Mario Minati