Minor documentation update in Resource
Minor documentation update in Resource

* Updated Resource#eql? to be more strict, matching the Ruby convention
  where it checks for equality with the same type of object, while
  Resource#== checks for equivalence with other objects

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