Fixed the file upload tests on windows

Some drivers are expecting the path to the file to use the right directory
separator, unlike PHP which accepts / on all platforms.
Applying realpath on the path will normalize this on Windows.
Merge pull request #543 from stof/fix_windows

Fixed the file upload tests on windows
Fixed the CSS hover test for the right-click event

When using a real right-click, browsers will open the context menu and the
mouse will be over the menu rather than over the element. This prevents
the hover styles from being applied.
Merge pull request #544 from stof/rightclick_hover

Fixed the CSS hover test for the right-click event
Renamed the method of the XPath Escaper class to escapeLiteral
Moved the Form tests to a dedicated namespace in the testsuite
Merge pull request #547 from stof/form_tests

Moved the Form tests to a dedicated namespace in the testsuite
Merge pull request #546 from stof/rename_escaper_method

Renamed the method of the XPath Escaper class to escapeLiteral
Changed the DOCTYPE to html instead of XHTML 1.1 in all fixtures

Closes #533
Merge pull request #552 from stof/html_doctype

Changed the DOCTYPE to html instead of XHTML 1.1 in all fixtures
Added tests for the handling of radio buttons in the driver suite

Refs #545 and #526
Moved a test to the RadioTest class as it works with radio buttons
Merge pull request #554 from stof/radio_tests

Added tests for the handling of radio buttons in the driver suite
Improved the phpdoc of form actions on elements to describe the behavior

Refs #526
Merge pull request #553 from stof/phpdoc

Improved the phpdoc of form actions on elements to describe the behavior
Moved the existing select tests to a dedicated testcase
Added a test covering the selection with reset in multiple select boxes
Added tests ensuring setValue can be used for select boxes
Moved the test for select options without values to SelectTest

Having this test in the JS tests does not make sense. The test does not
involve any javascript.
Added the verification of isSelected for options without values