add failing test for weird has_many :uniq count bug we're seeing
properly set distinct if select_values starts with DISTINCT
Merge pull request #62 from github/3-0-github+has_many-count-with-distinct

Fix weird unique has_many count bug we're seeing
Fix require for class_attribute
Cheaper attribute_method_matchers

Conflicts:
	activemodel/lib/active_model/attribute_methods.rb
Fewer object allocations

Conflicts:
	activemodel/lib/active_model/attribute_methods.rb
allocate less objects
don't bother checking for respond_to? here