Update dependencies with missing ones (Fix #237)

There was some missing dependencies, and some weirdness in the
package.json. This should be fixed. Bower and grunt-cli have been moved
back to the peerDependencies; if running on travis-CI or similar and
having issues, you should install those two in the pre-build script.

I send a PR because I'm unsure why/how the package.json file have reach the previous state.