some of the legacy sdk libraries call flush against localhost:11210/11211 if developer runs "make test"

if user builds and tests the sdk library on the same machine as the production environment and they run "make test" or run some of the unit tests its possible that the test invokes flush against port 11211 or 11210 and if production cluster has non-secure bucket "default" without a password it will flush the entire data from memory to disk and user can eventually lose data if they dont have backup to restore from.

in 1.8.1 release we are disabling flush command by default . user can enable flush by using cbflushctl command.