Refactoring of client and cli

[Cyber1000]

Preparation for using client-classes with something more server-centric (rest-service, mqtt, ...)

• Depends on #86 (including commits from there), so should be merged afterwards

Tasks

• [ ] Merge #86 before
• [ ] check set_values (with and without wifi) of http-protocol (2 TODOs in here - I don't know exactly the output - think it may be status: success, like in other implementations)

General information

• cleaned up client and cli classes
• client output changed (outputting raw and transformed values), cli output doesn't change (besides of smaller debug output changes)
• Every commit is a single change (more or less) to make it easier to review

Changes in clients

• moved CoAPAirClientBase to base_client.py
• AirClientBase is now a base for all clients (http, coap, plain_coap) and is for setting some base-values like logger, adds methods for getting the json in shape
  • this base-class takes a parameter debug, thus "debug" is not needed anymore in get and set-methods (was inconsistent between different protocols)
• Changed json in clients:
  • STATUS_TRANSFORMER is now used directly in client-classes to transform raw-values
  • description, name, subset, raw, value is added to json coming from the device
  • coap/plain_coap: filter, firmware always returned the full dataset (was reduced on client-side) - now client side only returns relevant data
• Runtime (in h) was modulo 24, so cut off afer one day
• removed get_status in favor of get_information (includes firmware and filters as well)
• changed ssdp to get_devices (if get_devices not possible - coap, plain-coap - an exception is thrown, which is caught by cli)
• moved set_wifi to set_values and added subset as switch

Changes in cli

• output in debug mode was changed to be json-compliant - see #78
• a new CLI_FORMAT is used here instead of STATUS_TRANSFORMER, which outputs things with user-friendly messages like "Pre-filter and Wick: clean in 5 hours"
• if you add "--debug" in addition to --filters, --firmware, --wifi you also get debug output
• after set_values is called also get_values is called
• simplified creation of clients by introducing class ClientFactory

example output of new client classes (see also Examples.md)

    "mode": {
        "name": "Mode",
        "raw": "A",
        "value": "allergen",
        "subsets": [
            "status"
        ],
        "rawDescription": null,
        "valueDescription": null
    },

[Cyber1000]

Since tests are still running without substantial changes (just refactoring issues), I'm assuming this PR doesn't break anything, thought I'm uncertain if #86 breaks connection with plain_coap.

[Cyber1000]

• To just see changes from this PR, have a look at https://github.com/Cyber1000/py-air-control/compare/coap...Cyber1000:refactoring-client-and-cli (sorry github doesn't provide dependant PRs)
• changes can be seen commitwise (sorry a lot of commits in this PR)

[wldevries]

Does anything need to happen before this can be merged?