MB-30041: Migrate parseErrorMap to nlohmann json
MB-30041: Migrate parseErrorMap to nlohmann json

Migrate settings.cc to nlohmann::json by migrating individual
handlers, which requires interim parsing of cJSON objects
to nlohmann::json objects.

Migrate parseErrorMap to nlohmann json to complete the migration
of settings.cc. Remove the cJSON includes.

Change-Id: Ie97a166b0e65e98f57546a417f07b755eb30796a
Reviewed-on: http://review.couchbase.org/101992
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Paolo Cocchi <9dd88c9f3e5cbab6e19a6c020f107e0c648ac956@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine