expand pkcs1 loader to load PKCS1 v1.5 and PSS signature examples
sign/verify
add docs
add padding
a bunch of PKCS1/PSS tests + todos
updates to match the interfaces that landed
hexlify things less stupidly
further stupidity reduction
flatten pkcs1 tests for parametrization
bytes and strings, two great tastes that go great together
copy hash ctx inside sign/verify to avoid use after finalize
move padding checks
add 0.9.8 support for PKCS1 v1.5 signatures.

skip PSS for now on OpenSSL < 1.0.0
trailing letters
PSS support in 0.9.8 *wipes brow*
remove openssl version checks
max length salt for PSS on 0.9.8
fixes for review comments
remove method that's now in another PR
raise AlreadyFinalized if finalize/verify called more than once