install fails if bower is not already installed

```
npm ERR! react-foundation-apps@0.6.1 postinstall: `bower install`
npm ERR! Exit status 127
npm ERR!
npm ERR! Failed at the react-foundation-apps@0.6.1 postinstall script.
npm ERR! This is most likely a problem with the react-foundation-apps package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! bower install
npm ERR! You can get their info via:
npm ERR! npm owner ls react-foundation-apps
npm ERR! There is likely additional logging output above.

npm ERR! System Linux 3.19.0-21-generic
npm ERR! command "/usr/bin/nodejs" "/usr/bin/npm" "install"
npm ERR! cwd /home/owen/projects/activatefan.club/client-src
npm ERR! node -v v0.10.25
npm ERR! npm -v 1.4.21
npm ERR! code ELIFECYCLE
```

Seems odd to expect bower to be installed. If you're going to depend on it, you could add it as a dependency of this package (or better yet skip bower entirely and just install foundation-apps via npm: https://www.npmjs.com/package/foundation-apps).