Fix pep8 tests

[sashi-coursera]

$ pep8 coursera_autograder tests
/usr/local/lib/python3.8/site-packages/pep8.py:109: FutureWarning: Possible nested set at position 1
EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
coursera_autograder/commands/common.py:54:1: E302 expected 2 blank lines, found 1
coursera_autograder/commands/common.py:64:1: E302 expected 2 blank lines, found 1
coursera_autograder/commands/grade.py:30:10: E401 multiple imports on one line
coursera_autograder/commands/grade.py:41:15: E231 missing whitespace after ','
coursera_autograder/commands/grade.py:184:29: E251 unexpected spaces around keyword / parameter equals
coursera_autograder/commands/grade.py:190:29: E251 unexpected spaces around keyword / parameter equals
coursera_autograder/commands/upload.py:187:80: E501 line too long (99 > 79 characters)
coursera_autograder/commands/upload.py:190:14: E128 continuation line under-indented for visual indent
coursera_autograder/commands/upload.py:191:14: E128 continuation line under-indented for visual indent
coursera_autograder/commands/upload.py:191:80: E501 line too long (87 > 79 characters)
coursera_autograder/commands/upload.py:192:14: E128 continuation line under-indented for visual indent
coursera_autograder/commands/upload.py:192:80: E501 line too long (92 > 79 characters)
coursera_autograder/commands/upload.py:198:1: W293 blank line contains whitespace
coursera_autograder/commands/upload.py:320:80: E501 line too long (106 > 79 characters)
coursera_autograder/commands/upload.py:413:16: E251 unexpected spaces around keyword / parameter equals
coursera_autograder/commands/upload.py:413:18: E251 unexpected spaces around keyword / parameter equals
coursera_autograder/commands/upload.py:422:16: E251 unexpected spaces around keyword / parameter equals
coursera_autograder/commands/upload.py:422:18: E251 unexpected spaces around keyword / parameter equals
coursera_autograder/commands/upload.py:425:80: E501 line too long (85 > 79 characters)
coursera_autograder/commands/upload.py:426:80: E501 line too long (90 > 79 characters)