Add modal API
Merge branch 'notification_api' of https://github.com/mikepack/capybara into modal

* 'notification_api' of https://github.com/mikepack/capybara:
  Add modal API
Add adjustable wait time and text matching for modals
remove unnecessary respond_to_prompt, change parameter name from :response to :with to match fill_in, take text/regex to match as optional inline parameter instead of option
document expected behavior of Driver#accept_modal and #dismiss_modal
Merge pull request #1322 from jnicklas/modal

API for operation with modal dialogs