feat(nsq_consumer): Add input plugin

to consume metrics from an nsqd topic

closes #1347
closes #1369

plugins/inputs/nsq_consumer/README.md

@@ -0,0 +1,25 @@
+# NSQ Consumer Input Plugin
+
+The [NSQ](http://nsq.io/) consumer plugin polls a specified NSQD
+topic and adds messages to InfluxDB. This plugin allows a message to be in any of the supported `data_format` types. 
+
+## Configuration
+
+```toml
+# Read metrics from NSQD topic(s)
+[[inputs.nsq_consumer]]
+  ## An array of NSQD HTTP API endpoints
+  server = "localhost:4150"
+  topic = "telegraf"
+  channel = "consumer"
+  max_in_flight = 100
+
+  ## Data format to consume.
+  ## Each data format has it's own unique set of configuration options, read
+  ## more about them here:
+  ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
+  data_format = "influx"
+```
+
+## Testing
+The `nsq_consumer_test` mocks out the interaction with `NSQD`. It requires no outside dependencies.