test against Rails 4.0.0.rc2 and Rails 4.1 (edge)
Exclude reorder for count queries.

It turns out reorder behaves differently on Rails 3.1 and requires
explicit exclude to not pollute count query with order clause.
Rails 4 compat: AR::Base.silence requires an argument
Rails 4 compat: port named scopes to new syntax

Subtle edge case bugs pop up in AR 4 when named scopes are declared with
the old syntax. This is likely a bug with AR, but work around it for now.