Install a specific version of npm for caret version support in subprojects

Author: Lloyd Watkin

.travis.yml

@@ -5,6 +5,7 @@ before_install:
   # https://github.com/travis-ci/travis-cookbooks/issues/155
   - sudo rm -rf /dev/shm
   - sudo ln -s /run/shm /dev/shm
+  - npm install -g npm@~1.4.6
   - npm install -g grunt-cli
 language: node_js
 node_js: