Install latest npm in basebuild.sh

Change-Id: I96912caf72b5fb016a217e7a6dee34d5f48cc23b
diff --git a/packer/provision/basebuild.sh b/packer/provision/basebuild.sh
index 36857b6..6946432 100644
--- a/packer/provision/basebuild.sh
+++ b/packer/provision/basebuild.sh
@@ -43,6 +43,7 @@
         zip
         # end of apt-get install list
 
+    npm install -g npm@latest # install latest npm, since apt installs old version (v3.5.2)
     npm install -g bower
     npm install karma --save-dev