Submitting finished htmlbroom code

See: https://github.com/GigaOM/gigaom/issues/4979
instead of `$this->strip_attribs()` (which will execute right here immediately) you want to only run that in context of the `content_save_pre` filter.  So, do that like you hooked `init` about: `array( $this, 'strip_attribs' )`