Fixed json format in package.json.

Fixes the following error that occurs otherwise on running 'sudo npm install volo-appcache' :

npm ERR! Failed to parse json
npm ERR! Unexpected string
npm ERR! File: /home/siva/code/ffapps/gaia-chrono-app-master/package.json
npm ERR! Failed to parse package.json data.
npm ERR! package.json must be actual JSON, not just JavaScript.
npm ERR! 
npm ERR! This is not a bug in npm.
npm ERR! Tell the package author to fix their package.json file. JSON.parse

npm ERR! System Linux 3.2.0-36-generic-pae
npm ERR! command "/usr/local/bin/node" "/usr/local/bin/npm" "install" "volo-cache"
npm ERR! cwd ~/code/ffapps/gaia-chrono-app-master
npm ERR! node -v v0.8.18
npm ERR! npm -v 1.2.2
npm ERR! file ~/code/ffapps/gaia-chrono-app-master/package.json
npm ERR! code EJSONPARSE
npm ERR! 
npm ERR! Additional logging details can be found in:
npm ERR!     ~/code/ffapps/gaia-chrono-app-master/npm-debug.log
npm ERR! not ok code 0