WIP: Add docker bridge
Sync w/ docker containerizer networking modes
Rewrite random host port bindings in DockerInfo
Added Mesos JAR from 0.20.1 staging repo
Updated for network mode enum name in mesos.proto
Updated Mesos dependency to 0.20.1
Added bridged networking info to docs
More docker bridge docs & examples
Capture dynamic ports specified in container

- Adds AppDefinition.containerHostPorts()
- Adds test cases to GroupManagerTest
Updated apps collection example in REST doc
Added to bridged networking part of docker doc
Upgraded to mesos-utils for 0.20.1
Improved logging in TaskBuilder, PortsMatcher
Merge pull request #621 from mesosphere/docker_bridge

Docker bridge