wrap named_scope options in a lambda so that conditions such as Dates/Times don't cache for chained named scopes
remove the arity==0 check again so that chained scopes aren't cached
add a spec to support our change for supporting lambda conditions when chaining a named_scope through an association
Merge pull request #168 from szTheory/master

remove the arity==0 check again so that chained scopes aren't cached