Merge pull request #17 from rayrod2030/feature/add-support-for-trusty

Add support for Ubuntu 14.04 Trusty 

Note: This is a workaround until a trusty mesos deb is available rom the mesosphere site.
bump default version to 0.18.2
Bump version to 0.19.0.

Download url tricks are in mesosphere and docker-executor recipes because they have changed download url conventions.
Merge branch 'master' of https://github.com/everpeace/cookbook-mesos