Added full support for raindrops and tests

plugins/inputs/raindrops/README.md

@@ -0,0 +1,15 @@
+# Raindrops Input Plugin
+
+The [raindrops](http://raindrops.bogomips.org/) plugin reads from
+specified raindops middleware URI and adds stats to InfluxDB.
+### Configuration:
+
+```toml
+# Read raindrops stats
+[[inputs.raindrops]]
+  urls = ["http://localhost/_raindrops"]
+```
+
+### Tags:
+
+- Multiple listeners are tagged with IP:Port/Socket, ie `0.0.0.0:8080` or  `/tmp/unicorn`