Fix request parameter in postTimespan

Server.hs: Fix postTimespan to read timespanEndMin from "endMin"
parameter rather than "endMax".

Spec.hs: Change timespanEndMin from 10.0 to 9.0 in firstTimespans to
correspond with initTimespan.

Signed-off-by: Stian Ellingsen    <stian@plaimi.net>
Reviewed-by:   Alexander Berntsen <alexander@plaimi.net>
Signed-off-by: Alexander Berntsen <alexander@plaimi.net>