fix node 0.8 Travis CI failure

Due to outdated npm not understanding ^ in semver versions.

Ref: https://github.com/One-com/livestyle/commit/c19e7d6bdbf11aef81f04f7bac17ad4cf0de691c
Merge pull request #125 from assetgraph/feature/travis-node-0.8

fix node 0.8 Travis CI failure