Migrate to official logstash packages; build out test framework; HAproxy; Nginx; UUID

This PR is designed to (at least partially) un-diverge a bunch of branches:

* pkg_update
* statsd_and_archive_replay
* x_request_id

It does the following:

* Migrates to the use of the elasticsearch logstash repo
* Upgrades to logstash v1.4.2
* Moves to 'conf.d' format configuration
* Adds a 'per-filter file' configuration testing framework in custom-test/
* Adds prefixes to any use of 'kv' -- we were overwriting fields like 'type'.

I have not focussed on maintaining compatibility with the various branches -- the field names will in many places will be different. We were doing things quite badly though, so this should be considered a base to move forwards from.

I've tried to make an effort to conform to a 'best practices guide' that I'm putting together, an early version is available at: https://gist.github.com/mikepea/443d1e07c430d447fd73 


Agreed. We also need to see if using the binary port can lead to more split brain cases where this would end up with two 'nodes' giving this box more weighting than it should have. (I'm basing this off a few conversations where someone, (you?) said that the binary port effectively makes Logstash part of the ES cluster)