wip
Expose app versions in UI

* Add model and collection for AppVersion
* Expose all versions in the “Configuration” tab
* Roll back to previous versions via a button on the version row
Rename JSX files to .jsx for new compilation setup
Add dependency lost in rebase
Use `map` to render app versions
Adding folding to the app version list
Adding styles to list
First draft, WIP, app versions
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