-------------------
* updated :code:`TimeoutExpired` and :code:`CalledProcessError` exceptions to
inherit from their counterparts in the Python standard library
* added :code:`encoding` parameter to :code:`Popen` to allow users to specify
which encoding, if any, should be used to decode the output stream from a
process.
* added :code:`volumes` parameter to :code:`provision` method in
:code:`DockerDaemon`, allowing users to specify volume mounts.