MB-9315: Use <1|0> to indicate demandEncryption

Based on spec, ns_server expects number instead of true|false

Change-Id: I47d3fe18fce4693ca723ee69dcda9e2669e395dd
Reviewed-on: http://review.couchbase.org/31588
Reviewed-by: Steve Yen <steve.yen@gmail.com>
Tested-by: Bin Cui <bin.cui@gmail.com>