[TACHYON-30] cephfs as under filesystem

This makes cephfs as a new under filesystem.

The unit test environment is created by vagrant, detailed information can be found at vagrant/README.md.

I leave the door open but it is possible we are going to use single condition using pseudo code like the following, and we can consolidate both ceph, gluster, and many other hdfs like fs.

if (is_hdfs(fsDefaultName)) {
  // hdfs and its compatibles can be configured through core-site.xml
  tConf.addResource(...)
}else{
 // posix compliant fs goes here
} else {
 // other variant
}