Read command line options from MARATHON_* environment variables like meos-master/slave.

This could be very useful when you start marathon with docker.  If we had a docker container in which marathon was installed , we can start marathon like this.

```
$ docker run -e "MARATHON_master=zk://localhost:2181/mesos" -e "MARATHON_zk=zk://localhost:2181/marathon" marathon /marathon-0.6.1/bin/start
```
Support env varibales with all CAP like MARATHON_ZK.
service start script also supports MARATHON_*
paved document for supporting environment variable to set options.
Documented that all command line options precedes environment variables.
Adding minimum progress step of 0
Re-compiling sources
Merge pull request #691 from mesosphere/bugifx/negative-deployment-step

Adding minimum progress step of 0
Regognize all terminal states in StoppingBehavior
Merge pull request #692 from mesosphere/terminal-states-stopping-behavior

Regognize all terminal states in StoppingBehavior
Add a HistoryActor and a TaskFailureEventRepository.
Expose task failure in API.
Add a test to check AppFailures deleted correctly.
Cleanup: initial task failure API response

- Fixed logic to NOT count TASK_KILLED as failure
- Renamed TaskFailureEvent => TaskFailure
- Augmented TaskFailure (state, host, taskId, etc)
- Added custom TaskFailure extractor object
- Added TaskFailure protobuf (un)marshaling
- Added JSON (de)serializer for o.a.m.P.TaskID
- Added TaskFailure proto/JSON tests
- Deleted some unused code in HistoryActor
- Added explicit return types to public methods
- Added usage to the REST docs
- Fixes #482
Added lastTaskFailures to GET /v2/apps/{appId}

- Updated REST docs with new response
Merge pull request #686 from mesosphere/wip-task-failures

Latest Task Failure in App Response JSON
Reflecting comments by Connor Doyle.
Merge pull request #475 from everpeace/feature/read_env_var

Read command line options from MARATHON_*.
Made test task depend on scalastyle in build
Merge pull request #695 from mesosphere/strict-style

Made test task depend on scalastyle in build