Upgrade rspec to 2.99
Convert specs to RSpec 2.99.1 syntax with Transpec

This conversion is done by Transpec 2.3.1 with the following command:
    transpec

* 23 conversions
    from: obj.should
      to: expect(obj).to

* 15 conversions
    from: be_true
      to: be_truthy

* 4 conversions
    from: describe 'some controller' { }
      to: describe 'some controller', :type => :controller { }

* 4 conversions
    from: obj.should_not
      to: expect(obj).not_to

* 2 conversions
    from: > expected
      to: be > expected

* 2 conversions
    from: describe 'some model' { }
      to: describe 'some model', :type => :model { }

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Adds rspec/collection_matchers; fixes deprecations in user_spec.rb
Removed deprecation from admin_posts_controller_spec.rb
Upgrade rspec to 3.x
Removed rspec/autorun