Allow Formo::add_rule() to use a syntax similar to Validation::rule().

[shadlaws]

This allows a syntax similar to Validation::rule() and Formo::remove_rule() as

$field->add_rule($rule);
$field->add_rule($rule, $params);

or a syntax similar to Validation::rules() and Formo::add_rules() as

$field->add_rule(array($rule));
$field->add_rule(array($rule, $params));

Not only does this make our implementation code a little cleaner (working on updating Gallery to Kohana 3.3 at https://github.com/gallery/gallery3/tree/kohana_3), but it also makes it easier to extend add_rule(). FWIW, I'm extending add_rule() to allow inline error message definitions (inline as opposed to in message files, that is)...

Thanks!

[bmidget]

Looks good. I've added you as a Formo collaborator. Please make sure you match Formo style and quality of code and update docs as well with changes.

[shadlaws]

Thanks much - I appreciate it! And thanks also on all the work you've put into Formo!