find(:all) and find(:first) ignore :cast=>true

[mbklein]

ActiveFedora::Base.find(conditions, :cast=>true) adapts the response to its first declared CModel. Principle of Least Surprise would expect ActiveFedora.find(:first, :cast=>true) and ActiveFedora.find(:all, :cast=>true) to do the same, but they don't.

[jcoyne]

ActiveFedora::Base.find(:all) is just a shortcut to ActiveFedora::Base.all, which is there to preserve backwards compatibility. ActiveFedora::Base.all should always cast to the appropriate cmodel.

I've deprecated the :all, :first, and :last options in this PR:
#201

[mbklein]

Cool. +1