Add SHA-3 support

[fxdupont]

Please hold:

• OpenSSL has a bug in HMAC code (HMAC_MAX_MD_CBLOCK publicly defined with a too small value), cf issue #4335
• Botan has (had!) a bug impacting RSA PKCSv1.5 with SHA-3 (note the DNSSEC IETF draft uses RSA PSS following a comment I sent to authors)
  So there are a few things to finish (i.e. I pull this mainly to show what could be done).
  SHA-3 is supported for hash, hmac (but see OpenSSL note), rsa pkcs (but see Botan note) and rsa pss (should be checked for DNSSEC soon).

[pawal]

Does Botan and OpenSSL still has these problems?

[vladislav-kovtun]

HMAC_MAX_MD_CBLOCK has been deprecated by OpenSSL. Documentation by OpenSSL suggests that it should be replaced with EVP_MAX_MD_SIZE instead.

[jschlyter]

Please rebase on develop and mark as ready when ready.