Make attach_to_url work with partial urls in selenium.

The attach_to_url RDoc claims partial urls should work, but they don't
  work in Selenium since there is a == check instead of a .include?.

* Add assertion to the attach to window then steps to verify that the
  attach generated an expected result.
* Add test to expose functionality. With the existing logic, selenium
  would iterate through all the existing handles until it found a full
  match on the url. The existing attach_to_url test wasn't hitting the
  full match, but the last handle switched to was the one looked for, so
  existing test passed by accident.
* Change selenium's attach_to_url implementation to use .include?.
Removed double_click from base PageObject::Elements::Element, and added it to Watir and Selenium platform elements to use Selenium::WebDriver::Mouse.double_click(element) when running in the selenium driver.

Also added a Scenario to the Element feature to test this functionality.  Adding a new html page was required to support this test
Added CSS support for all elements in Selenium, since Selenium supports it
Fix an incorrect comment
Added initialize_accessors similar to initialize_page.

This allows accessors to be added at object instantiation instead of
compile time.

One example use is localized accessors.
Cleaned up test for initialize_page

I don't think the test for initialize_page was working correctly.
Merge pull request #136 from gshakhn/attach-to-window-partial-url-fix

Make attach_to_window work with partial urls in selenium.
made changelog entry for pull request
Merge pull request #140 from wjpowell/master

Resolved double_click issue for Selenium
fixed specs for double_click and added changelog entry
Merge pull request #142 from bmulholland/add-selenium-css

Add CSS Locators For All Objects When Using Selenium
added changelog entry for pull request
Merge pull request #143 from trcjr/develop

Added initialize_accessors similar to initialize_page.
added changelog entry for pull request
version bump for release
Working on improving extensibility of Page-Object
tests passing for dynamic extension of PageObject.
starting to incorporate widgets into feature tests.
adding extension class into feature folder.
updated to use latest watir-webdriver and selenium-webdriver