add service check for gunicorn based on running workers
added messages to svc for # working and # idle workers
Add tokumx service check
Fix service check name
use better replica detection method

Fixes #1182
Merge branch 'master' into gunicorn-svc
cleanup
Make installation script ready for 5.1.0 and pup removal
Fix header conflict

Fix #542
Do not display warning about ssl certificate validation being disabled if not using https

And add a test for that
Fix #1195
Test the headers
Merge pull request #1197 from DataDog/fix_http_check

Fix http check
Fix nagios default configuration
Add service check for Kyototycoon.
Add CouchDB service check.

Pretty much the same as how it works in Couchbase with a test.
Add service check to elastic search for connectivity
Small fixes as per Conor's comments
Fix spacing
Only collect relevant Docker metrics by default

Add collect_all_metrics option to collect all the others
Disable tagging by hostname by default for HAProxy service check.

In general you care about a {backend,service} combination but not the
HAProxy host itself. With tagging by host, the default setup for an
HAProxy monitor will trigger N errors everytime a backend goes down,
where N is the number of haproxy load balancers.

This will make things less noisy but keeps an option to enable the
tagging by hostname if you would like it.

I also updated the formatting on the YAML file to match the HTTP
check so it's more readable/clear.