Mesos integration of Apache Flink

Hi,

this PR is a mesos client for Flink. It still needs to be tested which i will do as soon as I have access to a cluster. On a single machine with mesos running it works fine. Even though it is not ready to merge, I want to gather feedback and suggestions on it. 

I tried to make everything as similar to the yarn client as possible. For an idea on how this works there is a mesos_setup.md.