NSQ Output plugin

NSQ output plugin, following the NSQ methodology output is a producer
to one instance of NSQD. The go library does not accept array values be
default for a Producer. Additionally service discovery is generally
done as a consumer.

Follows same methodology as Kafka Output without the tag reference.

outputs/nsq/README.md

@@ -0,0 +1,4 @@
+# NSQ Output Plugin
+
+This plugin writes to a specified NSQD instance, usually local to the producer. It requires
+a `server` name and a `topic` name.