[Tachyon-191] deploy tachyon cluster on openstack

1) Deploy Tachyon cluster on OpenStack Compute Node. 
2) Fix AWS provider ssh key issue. Previously AWS provider worked thanks to left over ssh keys in `files` directory that got uploaded to VPC instances and make them able to ssh to each other without problem. But on a clean environment where these keys are absent, the instances fail to communicate. The fix is to wrap up AWS provider in a script that does `configure`, `generate ssh key`, then `provision` to ensure the keys are in place before `vagrant provision` kicks in.
3) add regression test script to automate test process.

Tested on RedHat openstack cloud.
@haoyuan @dcapwell @hsaputra @childsb @calvinjia