add sign/verify ctx creation methods to RSABackend interface
add AsymmetricSignContext, AsymmetricVerifyContext, AsymmetricPadding
add docs for sign/verify ctx creation interface
+ docs for AsymmetricSignContext, AsymmetricVerifyContext, AsymmetricPadding
add versionadded to AsymmetricPadding
create_rsa_sign_ctx->create_rsa_signature_ctx
more renaming
some grammar fixes, rename a method or two
let's try renaming everything I said I'd rename
79 characters ought to be good enough for any line
Merge pull request #634 from reaperhulk/rsa-signing-interfaces

RSA Sign/Verify Interfaces