rollup by contacts failures

Don't merge just yet. This is just to raise visibility of the progress of this branch. There's still a lot to do. 

- rollup threshold is added to the contact model, api and web gateways
- gems updated to latest (bundle update) including tzinfo, active_support, rspec, etc

I'm updating the wiki docs as I go and pushing to my fork of them at https://github.com/jessereynolds/flapjack/wiki (particularly Redis Data Structure and API pages).