A new OVN maintenance method is added. This method lists all existing
OVN SB Chassis registers and checks if any of them has the same
hostname. In case of having duplicated "Chassis"/"Chassis_Private"
registers, the maintenance method will remove those with older
(lower) timestamp, that is stored in
"Chassis_Private.nb_cfg_timestamp", leaving only the newer one.
Closes-Bug: #2016158
Change-Id: Ib3c6f0dc01efd31430691e720ba23ccb4ede65fa
Rodolfo Alonso Hernandez
9d9f47c20c