Fix: Include require 'capybara/dsl'

Without requiring 'capybara/dsl', I was receiving an unitialized constant error. This fixes the problem. Here is a trace:

/Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/capybara-angular-0.0.3/lib/capybara/angular/dsl.rb:4:in `<module:DSL>': uninitialized constant Capybara::DSL (NameError)
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/capybara-angular-0.0.3/lib/capybara/angular/dsl.rb:3:in `<module:Angular>'
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/capybara-angular-0.0.3/lib/capybara/angular/dsl.rb:2:in `<module:Capybara>'
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/capybara-angular-0.0.3/lib/capybara/angular/dsl.rb:1:in `<top (required)>'
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/capybara-angular-0.0.3/lib/capybara/angular.rb:3:in `require_relative'
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/capybara-angular-0.0.3/lib/capybara/angular.rb:3:in `<top (required)>'
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/bundler-1.3.5/lib/bundler/runtime.rb:81:in `require'
	from /Users/james/.rvm/gems/ruby-2.0.0-p195@medeo-rails/gems/bundler-1.3.5/lib/bundler/runtime.rb:81:in `rescue in block in require'