LP1116258 - Hide download circ history if none to be found

As noted in LP1116258, if there is no circ history for a patron, but they
click on the Download CSV button, it leads them to unhappy server errors.

So, hide the Download CSV button unless the number of circs > 0.

Signed-off-by: Ben Shum <bshum@biblio.org>
Signed-off-by: Pasi Kallinen <pasi.kallinen@pttk.fi>