Update RSpec to v3

Update email_spec and launchy so dependencies for RSpec 3 are satisfied.
Convert specs to RSpec 3.0.4 syntax with Transpec

This conversion is done by Transpec 2.3.7 with the following command:
    transpec --keep oneliner --convert stub_with_hash --boolean-matcher true,false -t -p

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

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

* 4 conversions
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

* 3 conversions
    from: be_true
      to: be true

* 2 conversions
    from: Klass.any_instance.should_receive(:message)
      to: expect_any_instance_of(Klass).to receive(:message)

* 2 conversions
    from: Klass.any_instance.stub(:message => value)
      to: allow_any_instance_of(Klass).to receive_messages(:message => value)

* 2 conversions
    from: obj.should_not_receive(:message)
      to: expect(obj).not_to receive(:message)

* 1 conversion
    from: Klass.any_instance.stub(:message)
      to: allow_any_instance_of(Klass).to receive(:message)

* 1 conversion
    from: be_false
      to: be false

* 1 addition
      of: RSpec.configure { |c| c.infer_spec_type_from_file_location! }

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Fix deprecation warnings

* Update capybara, draper and fuubar to versions with RSpec 3
  compatibility
* Stop using `cancan`'s `be_able_to` matcher
* Remove `treat_symbols_as_metadata_keys_with_true_values` config option
Convert specs to RSpec 3.0.4 syntax with Transpec

With capybara updated, `RSpec.feature` will not work making this
conversion possible.

This conversion is done by Transpec 2.3.7 with the following command:
    transpec --keep oneliner --convert example_group --boolean-matcher true,false -t -p

* 13 conversions
    from: describe 'something' { }
      to: RSpec.describe 'something' { }

* 7 conversions
    from: feature 'something' { }
      to: RSpec.feature 'something' { }

* 1 addition
      of: RSpec.configure { |c| c.expose_dsl_globally = false }

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Remove generated comments and group config options
Enforce `expect` syntax for specs
Update to RSpec 3

* Update gems dependent on RSpec 2.x (email_spec)
* Convert to new RSpec syntax
* Update capybara, fuubar and poltergeist to support new RSpec syntax
* Enforce `expect` syntax