Make import ordering consistent

[nikochiko]

Changes proposed:

• Make import ordering consistent in get_token.py (where import json line came after the third-party and from-style imports).

• As the ordering was not according to PEP 8 I made some sample changes to see the differences clearly.

• In addition to PEP 8, I used Google's style guide for extended conventions.

The syntax PEP 8 recommends is:

Imports should be grouped in the following order:

1. Standard library imports.
2. Related third party imports.
3. Local application/library specific imports.

You should put a blank line between each group of imports.

So for example,

# standard libraries first, with direct imports first and then "from" imports
import os
import sys
from datetime import datetime

# similarly for third-party imports
import requests
import responses
from bs4 import BeautifulSoup

# then local/specific imports
from evalai.some_app import some_class
from evalai.some_other_app import some_other_class
.
.
.