Revert "MB-100 add operating_system field in ini file"

See http://review.couchbase.org/#/c/27185/ for explanation.

Change-Id: I3eae7061dee7329db3643a2243309aed66422467
Reviewed-on: http://review.couchbase.org/27208
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>