BUG 1016 - JSON|XML output with|without white chars

BUG 1016 - JSON|XML output with|without white chars

Pretty print formating can be turned on for XML | JSON output via URI parameter
prettyPrint=true.
In other cases (prettyPrint=false, other value, missing
URI parameter...) XML | JSON output are returned as stream of characters
without white characters.

Example of URI:
http://localhost:8080/restconf/config/opendaylight-inventory:nodes?prettyPrint=true

Change-Id: I459c9663cdf8bfc78b8df67d7338a44d77c18a5c
Signed-off-by: Jozef Gloncak <jgloncak@cisco.com>