Submitting finished htmlbroom code

See: https://github.com/GigaOM/gigaom/issues/4979
Three notes on the regex pattern:

1. Both single and double quotes can be used here, as well as maybe no quotes. We definitely would want to support both single and double quotes.
1. Possibly want to look for a negative match on the single or double quote, as in `[^"]*` (though more complex so that you can match whatever quote type opened the attribute).
1. Maybe don't want to use regex.