Acertmgr

Changes
* authority.v2: invalidate nonces after 2 minutes and re-request
* dns.*: Use a static query timeout for any DNS queries using dnspython

Changes
* Display warning about IDNA only if unicode names are in use
* authority.v2: Properly clear the nonce cache on using it's content
* authority.v2: Check challenge return code on validation as well

Changes
* Deprecate legacy configuration directives
* Support creating certificates with the OCSP-must staple extension (cert_must_staple)
* Add additional DNS challenge checks to speed up authorization (dns_verify_all_ns, dns_verify_server)
* Add support for non-RSA account keys
* Various bugfixes and optimizations

Changes
* Standlone Mode does no longer require webdir (challenges are now served on the fly)
* New config option: webdir_verify
* New commandline option: --force-renew
* New commandline options: --revoke and --revoke-reason
* New config option: cert_revoke_superseded