Removing Compatibility methods

It doesn't make sense to be both cryptographically secure and insecure
in the same library.
Replace most ecdsa funtions with OpenSSL

This allows us to easily write a pem file to disk and recreate the key
from the pem file. We were unable to remove the ecdsa gem entirely, the
OpenSSL library does not handle EC signatures.
add license information
remove broken cli functions, update key_utils