Bump plucky version and fix the build list to reflect the spec suite change

Author: cheald

mongo_mapper.gemspec

@@ -11,10 +11,10 @@ Gem::Specification.new do |s|
   s.executables        = ['mmconsole']
   s.version            = MongoMapper::Version
   s.platform           = Gem::Platform::RUBY
-  s.files              = Dir.glob("{bin,examples,lib,rails,test}/**/*") + %w[LICENSE UPGRADES README.rdoc]
+  s.files              = Dir.glob("{bin,examples,lib,spec}/**/*") + %w[LICENSE UPGRADES README.rdoc]
 
   s.add_dependency 'activemodel',   ">= 3.0.0"
   s.add_dependency 'activesupport', '>= 3.0'
-  s.add_dependency 'plucky',        '~> 0.6.3'
+  s.add_dependency 'plucky',        '~> 0.6.4'
   s.add_dependency 'mongo',         '~> 1.8'
 end