Bug 17708: Added a logaction function in Addrenewal in order to send renew logs

Bug 17708: Added a logaction function in Addrenewal in order to send renew logs

20/02/17 : added the syspref RenewalLog
24/20/17 : added a test for the syspref Renewal Log

test plan
1 - Chose a Borrower and have him renewing an item
2 - Check the renew logs : they should be empty
3 - Apply patch and set the syspref RenewalLog to 1
4 - Have the Borrower renewing a new item
5 - Check the renew logs : there should be your renew

I called the function logaction, which is in charge of modifying the
logs, within the function which adds a new renewal at the list.

Signed-off-by: Julien Comte <julien.comte@u-psud.fr>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>