Generate html overview

[branneman]

Generate a single html file as a comparison result, which has a nice overview of all different captures with the percentage.

[cstegeman]

+1!

[lazytesting]

I think it would be useful to have the option to hide differences on this page.

By example: if I have an expected difference in my footer component I would like to hide this component for all pages. This will speed up the manual comparison and reduce the chance of missing an unintended difference.