add tests for (model,controller) user
add test for ads_controller + refactory ability
replace will_paginate to kaminari
add respond_with
Merge remote-tracking branch 'origin/tests'

Conflicts:
	app/controllers/users_controller.rb
	app/models/ability.rb
Merge branch 'kaminari'
Merge branch 'replace_to_respond_with'

Conflicts:
	Gemfile