Added function keyword
Added function keyword

Trying to install this plugin from github (`ember install ember-cli-deploy/ember-cli-deploy-s3-index`) results in an error:

> Unexpected token (

This fixes it and I presume is intended behaviour unless you are somehow running npm through babel? I'm on node `v0.12.7`
elidupuis/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,vitch/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,ember-cli-deploy/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,vitch/ember-cli-deploy-s3-index,ember-cli-deploy/ember-cli-deploy-s3-index