Ordered plugin_list

Hi,

I have made a minor change to the code that would allow people to pull out the pluggins in the same order they were added to the object. This is something that we would like to do with our code and doesn't see mto break functionality for those that dont care about the order. 

I'm not sure if this should be an update to the existing module or a new module called Moosex::Role::Pluggable::Ordered, but I thought I would update the code and see if you wanted to pull it in. If you think the use of Tie::IxHash might break things for others, then I am happy to upload this as the Ordered module and inherit from yours. 

Regards, 

Jody