WIP: Refactor events controller

This is what I think would be a good strategy for creating use cases on what the controllers are doing: 
- For each use cases there should be a service object namespaced to know what is working on; example Events::Creator, this suggest to us which is what this service is doing. 
- Each service receive two callbacks or several to know what this services will do on different triggered situations 

This pull request also have an spec and this will lead us to separate and test actual business logic isolated from Rails. 

Please even if you merge this changes; I would love to see some discussion on this. I'm planning to write some wiki pages with more resources and information regarding this arch.