Bug 14735: Save cache_expiry on modifying a report

Bug 14735: Save cache_expiry on modifying a report

The cache_expiry is not saved when updating a SQL report.

Test plan:
0/ Enable memcached
1/ Create a sql report
2/ Edit it and change the cache expiry value
3/ Edit again
=> The value should have been updated.

Signed-off-by: Frederic Demians <f.demians@tamil.fr>
  Repeatable bug. Solved with this patch.
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

(cherry picked from commit 27a15d5a429620dbad0a16292d714e3389ea057e)
(cherry picked from commit eeb9a6c1e577245387604987a5ed1cd5c1ab1411)
Signed-off-by: Liz Rea <wizzyrea@gmail.com>