restructure some tests, add skip, use der_encode_dsa_signature
restructure some tests, add skip, use der_encode_dsa_signature

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