[TACHYON-127] WIP: Create Tachyon Cluster via Vagrant

While it is still work-in-progress, feedback is badly needed for this work. 

What's working?
We can start a two-VM Tachyon cluster using HDFS 2.4.1 as under filesystem.

What next?
- more under filesystem (ceph, gluster, hadoop 1.0.4)
- Docker provider
- AWS provider

@haoyuan @childsb @uronce-cc @dcapwell