wip
added models for groups and stub GroupsResource
UpgradeManager: interface defined
UpgradeActor: first sketch
DeploymentPlan: deployment steps to execute
UpgradeEvent: add success and failed events
GroupRepository: genesis
small changes
Group: add version
GroupRepository: basic persistence
Group: remove clutter
Group: Rest CRUD operations
Make group persistent
Proto: add definitions to proto
Stepping: rename to Step
Group: implement MarathonState hooks
GroupResource: use  GroupManager to implement the methods
GroupManager: handle state updates and trigger deployments
GroupRepository: copy/paste from AppRepository
added restart call
make restart fail if tasks fail to start
added events and fixed callback for startup
make EventBus mandatory
DeploymentStep: now has waitTime and a check function
DeploymentAction: now has tasks to kill
GroupRepository: load latest AppDefinition from AppRepository, when Group is loaded
ignore local mesos.proto
added DeployActor
DeploymentPlan: make it a MarathonState
marathon.proto: add proto messages
DeploymentPlan: rename scale->scaleUp, orig->original
DeploymentPlan: missing action
-ScalingStrategy: make it a trait with 2 cases: rolling and canary
-UpgradeManager: not needed any longer
-DeploymentPlan: stores the strategy as well, to be able to take over pending deployments