Install a python linter

[subzero10]

My Intellij IDE complains with style warnings and inconsistencies with PEP 8.
I think we should integrate python linter and include in our CI.
A quick google search brought up the following linters:

• Pylint
• flake8

@joshuap Do you have any experience/preference towards any of the above?

[joshuap]

I don't have a personal preference—what about you, @Kelvin4664? Otherwise I'd go with whichever seems more popular.

[Kelvin4664]

No personal preference either. I am good with either of both.

[dotysan]

Start with flake8. You can always add others later.

[dotysan]

I took an initial stab in PR #149 and cleaning up.