Change the use of String#demodulize to ActiveSupport::Inflector.demodulize
Change the use of String#demodulize to ActiveSupport::Inflector.demodulize

* We are trying not to use the String extensions for the inflections
  because we want to try to minimize the number of core/stdlib classes
  that we affect when using AS. Ideally we would not affect any, and I
  think this is a good long term goal, but for now we just don't want
  to make it worse.

tillsc/dm-core,alloy/dm-core,datamapper/dm-core,engineyard/dm-core,tpitale/dm-core,ar-dm/ardm-core