Pytest config.py

[AbbyTsai]

Pytest coverage for config.py. Makes progress on #1229

----------- coverage: platform win32, python 3.7.4-final-0 -----------
Name                            Stmts   Miss  Cover   Missing
-------------------------------------------------------------
server\__init__.py                 38     12    68%   19-21, 37-45
server\config.py                   69      0   100%
server\csp.py                       1      0   100%
server\errors.py                   18      8    56%   11, 16-17, 22, 27-28, 33-34
server\feature_policy.py            1      0   100%
server\helpers.py                 126      0   100%
server\language.py                 31      1    97%   10
server\routes.py                   59     30    49%   12, 18, 24-26, 32, 38-42, 48, 58-61, 78-82, 90-92, 98, 103, 109-112, 118
server\tests\__init__.py            0      0   100%
server\tests\config_test.py        25      2    92%   17-18
server\tests\helpers_test.py      183      0   100%
server\tests\validate_test.py      52      0   100%
server\validate.py                 78     33    58%   25-53, 59-72, 81-82, 104, 108-109
-------------------------------------------------------------
TOTAL                             681     86    87%
Required test coverage of 85% reached. Total coverage: 87.37%.

Note after discussion with @bazzadp we removed Gravatar support as not used and doesn't even work when we tested it!

[tunetheweb]

Very good first attempt @AbbyTsai !

I've suggested some improvements