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

This obsoletes #452 

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 and glusterfs as under filesystem.

What next?
- more under filesystem (ceph, hadoop 1.0.4)
- more providers: OpenStack, AWS.

@haoyuan @childsb @uronce-cc @dcapwell @hsaputra 
my bad, i was reading `set -x` from your prior comment.  yes, `set -e` is a good idea.