Don't report coverage on HHVM

Don't report code coverage to Scrutinizer CI due PHAR parsing problems on HHVM.
Improved live tests

* Extracted AbstractLiveTestCase, added tests for RadioGroup, added PageLiveTests
* Moved typified tests to HtmlElementsLive and improved tests
* Adjusted PageTest radio group test and extracted XPath to constant
* Updated inline docblocks
Merge pull request #75 from evangelion1204/create-page-tests

Added tests for pages via Mink