hadoop: simplify workingDir handling; add home directory
hadoop: simplify workingDir handling; add home directory

1. Simplifies the handling of paths by allowing them to be passed
around and manipulated in their fully qualified form. Before
paths are passed into native Ceph calls the path-only portion
is extracted.

2. Sets the initial working directory to be the default home
directory for a user (e.g. /user/<username>/).

Signed-off-by: Noah Watkins <86ecd7d1c53cf33a85014f7cab78876cb4491020@gmail.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph