upgrade appraisals
support default-on-slave for .pluck
fix rails 3.0/pluck
Merge pull request #7 from zendesk/ben/support_pluck

Support .pluck on slave by default
Merge remote-tracking branch 'origin/master' into ben/support_has_many_include_on_slave

Conflicts:
	gemfiles/rails32.gemfile
	lib/active_record_shards/default_slave_patches.rb
	test/connection_switching_test.rb