PUBAPI-442: Default to application/json, which makes v8 omit error backtraces
PUBAPI-442: Default to application/json, which makes v8 omit error backtraces

arekinath/sdc-cloudapi,joyent/sdc-cloudapi,arekinath/sdc-cloudapi,KrisShannon/sdc-cloudapi,misterbisson/sdc-cloudapi,KrisShannon/sdc-cloudapi,joyent/sdc-cloudapi,misterbisson/sdc-cloudapi