Add tag form

Add tags on form submission. This may be useful when moving between steps in a multi-step process.

<perch:form id="add_tag" app="pipit_members" method="post" tag="sometag,anothertag" r="/next-step">
    <perch:input type="submit" value="Next">
    <perch:input type="hidden" id="token" />
</perch:form>