Added new high performance HTTP Event Collector (HEC) output adaptor.

[damiendallimore]

With the recent release of Splunk version 6.3 we now have a new high performance data collector called the HTTP Event Collector (HEC), http://blogs.splunk.com/2015/10/06/http-event-collector-your-direct-event-pipe-to-splunk-6-3/

This should now be used over our legacy data collectors which have been available as output adaptors in Spring Integration for some time.

This pull request contains a new output integration adaptor for sending events to Splunk via HEC.

I also refactored the SplunkEvent class which was riddled with legacy logic that is now irrelevant.I also updated the output of the SplunkEvent class to produce simple JSON which is more optimal that KV pairs for Splunk.

Damien Dallimore (Developer Evangelist @ Splunk , ddallimore@splunk.com)

[artembilan]

Hello, @damiendallimore !

It's a honor for me to work directly with one of developers of the system for our Integration adapters.
And thank you very much for the contribution!

I've raised a JIRA (https://jira.spring.io/browse/INTEXT-201) on the matter to track and I'm sure it would be a good feature to release Spring Integration Splunk 1.2.0 after merging your PR.

Before we start to review and polish your PR, would you mind confirming that you have signed the CLA: https://github.com/spring-projects/spring-integration/blob/master/CONTRIBUTING.md?

After that revise, please, your point for PR and make it from the top level branch with the name like INTEXT-201 (lucky number though!), not from the master.
Since your change is enough big we may spend some to to review it and adding more commits, so we may break your local master, as well as mine 😄

Thank you again and looking forward to hear from your side!

[damiendallimore]

I've signed the CLA and issued a new PULL request from a new INTEXT-201 branch.

Thanks for your feedback :)

[artembilan]

Thank you for following up!
Closing in favor of #3 .