change the spam api call

change the spam api call

instead of having the /quarantine/spam api call return a
list of days with spamcount/average,

display directly the list of spams for the given timeframe
(default the last 24 hours) like the spamlist api call
and drop that

(because having a unix timestamp as part of the path is not
really nice, and with the gui restructuring, we do not
need the day summary)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>