extend list to retrieve be able to return all information

[igalic]

currently, ioc list is our most powerful tool to extract information from all jails, templates and releases. Best of all it comes with an output format that everyone can deal with: JSON.

however, it requires one thing: prior knowledge. Unlike get, which can return all properties, in list we need to know exactly what we're asking for, which in turn means duplicating knowledge in multiple tools

get like many others (#233) lacks an JSON output format option (#232, #231)
but our problems are a bit deeper than that: the global namespace of properties is polluted (#413).

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So here's some improvements we can make to libiocage, to make it easier to use from third-party tools — especially those written in not-Python:

• implement namespaces for properties consider placing rlimits in own namespace #413
• add a --verbose option to list, which outputs all properties

[gronke]

I suggest to write a tiny helper using the library to achieve output for scripting usage:

import iocage
import json

jail = iocage.Jail("myjail")

data = {}
for key in jail.host.defaults.config.keys():
  data[key] = jail.config[key]

print(json.dumps(data))