Support HDFS access for -T hadoop.

Previously Makeflow had to run on FUSE+HDFS to access files.

Here's an example:

env HDFS_ROOT_DIR=/hdfs/host:port/path/to/working-dir HADOOP_USER_TMP=/a/tmp/path/in/hadoop HADOOP_PARROT_PATH=/path/to/parrot_run makeflow -T hadoop --working-dir=hdfs://host:port/path/to/working-dir Makeflow

HDFS_ROOT_DIR is used as the sandbox by Parrot before running the job (it is passed as --work-dir to Parrot).
HADOOP_USER_TMP is just a directory in Hadoop where job status information is stored.
HADOOP_PARROT_PATH is the Parrot executable you want to use.