Support uses the raw html section in order to pass a video tag which is compatible with html5.

Video size and style should be handled by the "video" class in the css file.

…duplicate of the image css.

Code for the video extra has been extracted to a function to clean up a bit the if/elif/elif that is starting to
get pretty big. Maybe the other conditions could be extracted to their own method to clean up a bit. Once again,
there seems to be a lot of code duplication with image, so we may want to refactor images, videos, and audio as
a media type and have some kind of template method.

Basic unit tests were added to make sure that the extra was correctly added to the report when the extra was
requested.

…st-dev#260. These changes aimed at generelizing the

approach used to introduce media types to the project. Images and videos now use a method called
_make_media_html_div which generates the media div in a streamlined manner. Both _append_image and _append_video
use this method, to which they can pass their base string and class.

Unit tests were left untouched, as the changes only affect private methods.