Add 'ceph-rest-api'

Add 'ceph-rest-api'

ceph-rest-api is a Python WSGI module for accessing the Ceph cluster.
It supports most of the commands supported by the ceph CLI,
appropriately translated to HTTP GET/PUT requests.  It is not a
truly RESTful interface.

Not supported at this moment: "tell", "pg <pgid>", and "daemon"
commands.

Configuration options are specified in ceph.conf, specified with
-c/--conf or obtained from $CEPH_CONF, /etc/ceph/ceph.conf,
~/.ceph/ceph.conf, or ./ceph.conf.

-n/--name specifies the client name, used for the cluster
authentication key and for the ceph.conf section name (default
is client.restapi).

        restapi keyring = <keyring file>
        restapi public addr = listenIP:port (default 0.0.0.0:5000)
        restapi base url = <base path> (default /api/v0.1)
        restapi log level = (error, warning, info, debug)
        restapi log file = (default /var/log/ceph/<clientname>.log)

Primitive human-level command discovery is supported; GET from
BASEURL (say, http://localhost:5000/api/v0.1) will show an HTML
table of all commands and arguments, method supported, and help strings.

Signed-off-by: Dan Mick <dan.mick@inktank.com>