Added helper script to link yet not linked non-core packages

    This resolves issue #10

    Read details on non-core packages at http://meteor-universal.tumblr.com/post/111435518849/use-non-core-packages-for-your-meteor-apps

scripts/link-non-core-packages.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -e
+set -u
+
+# save current path and switch inside packages
+pushd "$(dirname $0)/../packages" >/dev/null 2>&1
+
+# test that there are some non-core packages
+if [ -d "non-core" ]; then
+
+  # change to non-core
+  cd non-core
+
+  # link all ./packages/non-core/pkg to ./packages/pkg
+  for pkg in $(find . -mindepth 1 -maxdepth 1 -type d); do
+    if [ -L "../${pkg}" ]; then
+      echo "Package ${pkg} is already linked."
+    elif [ -e "../${pkg}" ] || [ -d "../${pkg}" ]; then
+      echo "Package ${pkg} does already exist."
+    else
+      ln -s "${pkg}" ..
+      echo "Package ${pkg} linked."
+    fi
+  done
+
+fi
+
+popd  >/dev/null 2>&1