Instead of overwriting Kohana_Exception::handle() (which we were doing
in MY_Kohana_Exception) we instead use their existing template system.
gallery/views/kohana/error.php overrides system/views/kohana/error.php
and is the standard error template for all exceptions. Our version of
error.php figures out the appropriate view based on context (cli,
authenticated admin, guest viewing a 404, guest viewing a system
error) and delegates appropriately. Each delegated view has a narrow
responsibility.
This paves the way for us to add new error views per module. For
example, the rest module will define its own template in
Rest_Exception and then its exceptions can be rendered the way that it
wants (json encoded, in that case).
