ONOS Swagger Plugin

just does swagger now
to build the plugin, you need to download to following:
https://github.com/bocon13/buck/releases/download/v2016.07.29.01-wip/buck.jar

put the buck.jar in tools/build/buck-plugin/lib

Change-Id: Id1b833dd013fbc5581f8e884e755920829c4a17e
diff --git a/.buckconfig b/.buckconfig
index 3780ab0..283935c 100644
--- a/.buckconfig
+++ b/.buckconfig
@@ -1,6 +1,9 @@
 [buildfile]
   includes = //buck-tools/default.defs
 
+[plugins]
+  directory = //bucklets/plugins
+
 [java]
   source_level = 8
   target_level = 8