Hermes and Rails 4 <3

Bump dependencies to work with Rails 4 and Ruby 1.9.3 and 2.0.

Summary changes:

Ruby:
- `assert_block` is deprecated.

Rails 4 and friends:
- `Proc#bind` is deprecated.
- `ActionController::RecordIdentifier` is deprecated.
- `assign_attributes` only accept one hash attribute

Capybara:
- `find` doesn't accept `:message` param.
- `has_table?` now use `has_selector` and doesn't accept `:row` param.