Added support for mink-capybara-webkit-driver , Fixed / Added support for Screenshots in Outline Scenarios

I have added support for mink-capybara-webkit-driver  ( https://github.com/nstojiljkovic/mink-capybara-webkit-driver ).
Also I fixed / added support for Screenshots in Outline Scenarios .
Screenshots are now created as files in directory of report html file. 
Screenshots are used in html report as &lt;img src="Screen Shot 2014-09-11 14.36.59.png" /&gt; instead of <img src="data:image/png;base64.... in html file , because html file can be to big for some browsers...