Refactor elasticsearch search check so it has a clearer code path
Support basic authentication in Elasticsearch check.

Useful for 3rd party plugins and Elasticsearch PaaS like found.no
Remove changes to elasticsearch test as it broke the build on travis
Merge branch 'master' into elasticsearch-basic-auth
Fix the authorization string for Elasticsearch.

Also consolidate adding basic authentication to urllib2 requests into
one place.
Fix a typo in the example elastic yaml
Merge pull request #806 from DataDog/elasticsearch-basic-auth

Add basic authentication support to the Elasticsearch check.