Adding onos packaging buck rule and script

Change-Id: I0c909e6bf45197061f81f1705de05561c4c91d8d
diff --git a/.buckconfig b/.buckconfig
index ab7460b..2d6f94a 100644
--- a/.buckconfig
+++ b/.buckconfig
@@ -7,6 +7,7 @@
 
 [alias]
     onos = //:onos
+    package = //tools/package:onos-package
 
 [download]
   maven_repo = https://repo1.maven.org/maven2