only index when there are modules registered.
Do not track index-write metrics in DiscoveryWriter.
Track index batch sizes and how long they take.

Track sizes, even when they are zero.
But only write track duration when there is stuff to index.
Add unit to repose of Http reponse handler
Merge pull request #359 from gdusbabek/ES_metrics

Measure ElasticSearch write peformance
Do not use abort rejection handler for DiscoverWriter threadpool

Do not use abort rejection handler for DiscoverWriter threadpool. The
abort rejection handler throws an exception and causes work to be lost
if no worker is available for a job.

We do NOT want to throw away work, so use the default rejection handler
which effectively ensures all work is done, and effectively throttles
ingestion.
Configure DiscoveryWriter threadpool size by itself

The DiscoveryWriter threadpool does not need to be very big. Create
configuration new config options specific to DiscoveryWriter TP size for
maximum control when tuning.
Do not re-index existing metrics in ES

Use the `CREATE` optype to use the "put-if-absent" functionality in
Elasticsearch. This will cut down on extra and unnecessary indexing
operations and IO in elasticsearch.
Merge pull request #360 from chinmay-gupte/chinmay/return_units_with_http_query_response

Add unit to the respose of Http Rollup Handler
Merge pull request #361 from dlobue/dominic/indexing_perf_enhancements

Dominic/indexing perf enhancements
adding logstash plugin for blueflood
Merge pull request #11 from rackerlabs/master

Merging rackerlabs:master changes
adding the ability to process dictionary metrics
adding a hack to process json in a way that blueflood will like
added some error checking for different formats, added conf file to test hash metrics
adding the right configuration for testing hash metrics
fixed review comment - do not need content type to be configurable, since it always should be json for bf
using string formatting
fixed the names of the class, and the name of the json_metrics
Merge pull request #12 from GeorgeJahad/george/logstash-changes

fixed the names of the class, and the name of the json_metrics