Random fit algo

Implement and add unit tests for naive scheduling algorithm. First filter the agents to match the container configuration and than just randomly choose one. 

Constraints for now:
- cpu
- memory
- volumes

@peterbourgon @bernerdschaefer  @jmyounker  @soundcloud/iss  
Ah, I understand, now. The transformer `func transform` is currently collecting the complete delta between the desired state and the actual state, and scheduling all containers with a single invocation of the scheduling algorithm. You're right: that's not a "job", that's just a random collection of ContainerConfigs :)

With that in mind, I agree with your implementation: the scheduling algorithm should indeed schedule as much as it can, and return un-scheduled jobs separately. Cool!