Refactor the ConfigurationParserJSON for clarity.

This changeset doesnt change any functionality but only refactors
and properly comments the ConfigurationParserJSON.

Change-Id: Ic534336f5421e9c0e928520665bde454cee4f653
Reviewed-on: http://review.couchbase.org/29849
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>