Restore LVS sysctl priority of 50

The default Ubuntu precise sysctl.pp have priority 10,
and conflict with the LVS sysctl settings which, until now,
had equal priority. Due to file naming, the Ubuntu defaults were
executed last, and thus rp_filter was turned on, breaking LVS.

Change-Id: I36cf9790362244d996f50cf270c39875939a3b01