Change structure of video_reqs.json

video_reqs is now an ordered list which makes some other things
a lot easier to do. This changes the code that uses it to handle
the new structure.

This also fixes some issues with the verify command and the
"category" field which is a little special.
Add webedit

webedit allows someone to use their web browser to edit the
json files. It takes advantage of the fact that steve knows about
the structure of the json files and therefore can make it easier on
an editor.

Having said that, it's pretty basic. It isn't all-encompassing and
should be considered one of many tools steve provides to build
conference data.