Seperate client and server of FTP

[AlexDvorak]

fixes issues found in PR#1044 @cclauss

[AlexDvorak]

TravisCI is hanging on pytest probably due to the server running an infinite loop, should we add it to the ignore in the pytest command, or should I make it so it only accepts one connection? @cclauss

============================= test session starts ==============================

platform linux -- Python 3.7.1, pytest-4.3.1, py-1.7.0, pluggy-0.8.0

rootdir: /home/travis/build/TheAlgorithms/Python, inifile:

collecting 22 items                                                            

No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.

Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received

The build has been terminated

[cclauss]

Please close the server after one transfer but put comments in the code that describes that carefully. For extra credit, add a ONE_CONNECTION_ONLY = True constant to make the code easier to reconfigure.

[cclauss]

Also please remove this line and make sure the Travis test passes.
https://github.com/TheAlgorithms/Python/blob/master/.travis.yml#L41

[AlexDvorak]

(this is a seperate issue, but the actual FTP protocol does not operate as it does in client.py and server.py)

[cclauss]

One undefined name 's' https://travis-ci.org/TheAlgorithms/Python/jobs/568640601#L564

[cclauss]

It seems to be hanging our pytest discovery process. Perhaps put the code under an ìf name == "main":` block so that is not executed each time that pytest imports the file.

[AlexDvorak]

the entirity of client.py and server.py should be under the ìf name == "main":?

[AlexDvorak]

what should we do about this?
ERROR: file not found: pytest
That file is very much not working, but is that out of scope for this PR?

[cclauss]

Landed!! Well done!