Support raw PKCS#1 RSA keys.

[sebadoom]

The libraries we are using at the moment to validate tokens only support X.509 subjectPublicKeyInfo keys. PKCS#1 RSA keys should be supported as well. For more information see here: https://stackoverflow.com/questions/18039401/how-can-i-transform-between-the-two-styles-of-public-key-format-one-begin-rsa

[sebadoom]

Check if these are supported after updating libraries (stage 3).

[sebadoom]

In 375c9e1.