Geoff Lawler authored Apr 30, 2020 and Ryan Goodfellow committed Apr 30, 2020

Meant to run on XDCs, the xdctool does an ecileltic numver of things.
Currently it:

* attaches and detaches to and from a materalization
* spits out an ansible ID file based on an attached mtz

Once this is in the XDC, we can remove the confusing `mergetb attach`
command as the `xdctool attach` will take its place.

The ansible id created honors the `group` prop on a node.

Ex:
```
glawler@xdc:/tmp# mergetb pull hi 9db9a824-bf1a-464f-8e55-bea06b629c46
PUSH DATE: Thu Apr 23 19:14:56 UTC 2020
CREATOR: glawler
MODEL SOURCE:
import mergexp as mx

net = mx.Topology('lan3')

nodes = [net.device(name) for name in ['a', 'B', 'c']]
lan = net.connect(nodes)

for i,e in enumerate(lan.endpoints, 1):
    e.ip.addrs = ['10.0.0.%d/24'%i]
    e.ip.mtu = 9000

nodes[0].props['group'] = "server"
nodes[1].props['group'] = "client"
nodes[2].props['group'] = "client"

mx.experiment(net)

glawler@xdc:/tmp# ./xdctool ansible identity glawler hi one
[all]
B
a
c

[server]
a

[client]
B
c
glawler@xdc:/tmp#
```