CBQE-2405 delete erlang registry after
uninstall 3.0.x as shown in bug MB-11985

Change-Id: I1485215a8769fb79e2fe1021460921f74198289e
Reviewed-on: http://review.couchbase.org/41207
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>