Add support for docker-executor versions greather than 0.14
Update example Vagrantfile for docker-executor
Switch example slave isolation configuraiton to process to prevent cgroup conflicts with docker
Fix detection of an already installed mesos python egg
Merge pull request #15 from jalaziz/update-docker-executor

Support for docker-executor versions above 0.14
Update README.md about docker-executor.
adjust eggname resolution for docker-executor