switched call from mount_sql_and_params to build_relation
switched call from mount_sql_and_params to build_relation

Looks like the method was renamed in https://github.com/rails/rails/commit/a30b440debe87722c0c072555db7945181ceffde#activerecord/lib/active_record/validations/uniqueness.rb

I Googled up the reference from here: https://github.com/goncalossilva/rails3_acts_as_paranoid/pull/39

vahtel/acts_as_paranoid,RevoTechnology/acts_as_paranoid,igorsokolov/rails3_acts_as_paranoid,OpenGov/acts_as_paranoid,mvz/acts_as_paranoid,abulava/rails3_acts_as_paranoid,ActsAsParanoid/acts_as_paranoid,pavlos/acts_as_paranoid,drecom/rails3_acts_as_paranoid,goncalossilva/acts_as_paranoid,mvj3/rails3_acts_as_paranoid