Use pylint to Lint the unit test and loklak.py

[DengYiping]

settings() has been changed to a stand alone function. The corresponding document and sample has been changed.

[landscape-bot]

Repository health decreased by 14% when pulling eb41ddb on DengYiping:master into 6594345 on loklak:master.

• 9 new problems were found (including 2 errors and 6 code smells).
• 1 problem was fixed (including 0 errors and 0 code smells).

[sudheesh001]

Sorry @DengYiping Good attempt but can't let this pass, the repository health has fallen. Please feel free to make another pull request