Mesos task status fix and misc.

1. Mesos task status fix. On killing a task, status is appropriately updated to "KILLED" as opposed to "FAILED" earlier.
2. Auto-fetch artifact version from pom during vm provisioning (vagrant up).

0.1.0

Multi compose file support:
Mesos label -- fileName takes comma delimited multi-compose files as follows:
"fileName": " sample-web-app/docker-compose.yml,sample-web-app/docker-compose2.yml"

Pluggable code for LaunchTask:
This is supported via pf4j extension. Appropriate logic can be injected here as plugin implementation.
Default implementation for launchTask, retrieves compose-file names from mesos TaskInfo object. This method is to be over-ridden as needed on case by case basis. _launchTask()_ method should return list of compose files path