Testing

[Cyber1000]

Information about this PR:

• there are only small changes in old code (some return values, to make it better testable)
• this adds some classes for pytest
  • http-client/cli is tested with a small flask (http) server, simulating the device
  • both coap-clients/cli are tested with a coap server created by CoAPthon3 pip
    • I couldn't test the problem with very long answers (https://github.com/rgerganov/py-air-control/issues/35#issuecomment-631899965) cause between a CoAPthon3-client and a CoAPthon3-server it seems to work, maybe the problem is a bad coap-implementation of the device itself.
  • I'm testing client and cli were appropriate
• I've removed python 3.4 support, cause in coap_client.py I'm using .hex() (already merged this way in your master) and hex was added in python 3.5 . I found this problem while testing (help would work, but get and set wouldn't)
  • If you still want 3.4, I'll try to find a workaround
  • If not, I should adjust README, before merging
• I've added 3 TODOs (search "# TODO"), I don't know really if I should let them in, TODOs in Code tend to be forgotten, but I hope that PRs in the near future make them unnecessary
• plain_coap still uses test data from a coap device (I think they should be quite similar from the kind of output, but I don't know exactly), we may wait for #43 before merging

[rgerganov]

Thank you for your work. I will go through this next week.

[Cyber1000]

I've adjusted everything, except the iptables-hack (see the comment) Thanks for reviewing!