Add support for sending events to elasticsearch - a distributed,
RESTful, search engine built on Lucene (www.elasticsearch.org).
The output module is enabled via a configure option, and uses
libcurl to send the messages from rsyslog to elasticsearch.
This patch makes use of the earlier JSON quoting patch to ensure
valid JSON strings are sent to the server.
Signed-off-by: Nathan Scott <nathans@aconex.com>
