Provision ponsim_olt device with a customizable serial number

The implementation of the VOLTHA ponsim_olt device does not currently have the
ability to retrieve a serial number from the simulated OLT device. Every time you enable a ponsim_olt device, a new serial number is generated and assigned automatically to the logical device.

There should be a way to customize the serial number information when a ponsim olt container is started.  Providing this information will ensure that the device always gets recognized by ONOS during authentication.

"org.opencord.sadis" : {
"sadis" : {
...
"entries" : [

{ ... }

,

{ "id" : *"c34c2c2fb6da40f1ab5e9bc20e02375b"*, "hardwareIdentifier" : "00:1b:22:00:b1:78", "ipAddress" : "1.2.3.4", "nasId" : "B100-NASID" }

]
...