Refactor harvesters into microservices

[tmaiaroto]

Use https://github.com/koding/kite to take each harvester and put them into their own microservice. They may all end up running on the same server (different ports) and that's ok. The repo can even be restructured so that everything runs as a single binary without the microservices running on different ports... But the ability to separate each harvester on to a separate server is going to be one of the core focuses for version 2.0.

It's a matter of scale. Most users likely won't need this, but for SocialHarvest to truly be a flexible and modular platform, this is critical. There will be a message bus or data flow that allows people to add in new services that harvest different data into the system.

This may, of course, break database schema (and new storage solutions may be required) - which is why this won't be considered until version 2.0.