Option to turn off whitelist for tags and attributes

Turn off whitelisting filter (i.e., allow all through) by setting `allowedTags` or `allowedAttributes` options to `false`.

This was the simplest/quickest way for me to get the flexibility I needed in the moment for something I'm doing.  Not sure if it's a feature you'd want, or whether a different design would be preferable, but figured I'd offer this one anyway.