Currently logs in to Google Analytics and scrapes the realtime page for the active visitors number from the overview screen.
Usage:
rake 'run[your.google@account.com,googlePassword,http://api.yourdomain.com/update-metric]'
Your api should take a post variable 'value' which contains the updated count, i.e: {value: "3098"}
Make sure to initialise submodules to get CasperJS