Slow auto-farmer down, and farm toward cap
Add cache buster to session links; fix app reload.

Add a ?nocache=<%= new Date().getTime() %> query arg to links to join
sessions in an effort to ensure old cached redirects are not used.

When the facilitator iframe reloads, it wasn't clearing the
tellParticipants interval, resulting in errors from the stale (leaked)
handler firing on a no-longer-existing iframe.