Fix issues found in hotp with new flake8 configuration.
Fix issues found in hotp with new flake8 configuration.

bwhmather/cryptography,skeuomorf/cryptography,Lukasa/cryptography,dstufft/cryptography,Hasimir/cryptography,dstufft/cryptography,Lukasa/cryptography,Ayrx/cryptography,bwhmather/cryptography,Lukasa/cryptography,kimvais/cryptography,Ayrx/cryptography,Hasimir/cryptography,sholsapp/cryptography,Ayrx/cryptography,skeuomorf/cryptography,skeuomorf/cryptography,dstufft/cryptography,Hasimir/cryptography,kimvais/cryptography,Ayrx/cryptography,bwhmather/cryptography,bwhmather/cryptography,dstufft/cryptography,sholsapp/cryptography,kimvais/cryptography,skeuomorf/cryptography,Hasimir/cryptography,sholsapp/cryptography,dstufft/cryptography,kimvais/cryptography,sholsapp/cryptography