Provide support for multiple baseline images and browser to pvweb testing module.
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
ParaViewWeb testing needs the ability to test against multiple baseline images when do image-based comparisons. Also required is the ability to run a single test script against all known or supported browsers. In to provide this, we need to integrate python functionality explored by Roni Choudhury into the current vtk.web.testing module.