Actionview extensions hash

Started working on Spree upgrade to Rails 4.1.0 and noticed this error due to ActionView::PathResolver::EXTENSIONS being a hash rather than an array.

ActionView also was moved out of ActionPack but the build looks ok only with this change. Not sure yet that more changes are needed on versioncake to make it work 100% with rails 4.1.0 though.

hope that it makes sense

cheers