html2text munges hrefs containing tokens

The html2text package is used to produce a plain text version of HTML emails that don't have a separate plain text version.

If a token such as

{action.unsubscribeUrl} is used in the body or footer, html2 text incorrectly prepends the base site URL to the token (e.g., "http://example.com/{action.unsubscribeUrl}

"), which results in an incorrect URL in the final email.

Patch attached.