Make this repo conform to PEP8 standards

[mbernier]

Issue Summary

It looks like we're breaking all the rules - https://codeclimate.com/github/sendgrid/python-http-client/issues

Please update the code to fit PEP8 standards.

[jlindenger]

I spent a few minutes knocking out your PEP8 issues. There were a few more in there that I didn't see showing up on CodeClimate as well.

[Madhur96]

I want to work on this