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

Change-Id: Iaed9431e9dee9b7b8ba6ddbd803797ab14b3a4b7
Reviewed-on: http://review.couchbase.org/41209
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>