Make source Erlang R14 compatible

In Erlang R14 erlang:integer_to_binary/1 didn't exist, replace it
with list_to_binary(integer_to_list/1).

Change-Id: I2377aa992d43f8f9e46776049d9aa764470fdced
Reviewed-on: http://review.couchbase.org/40506
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>