YKmap:  Add support for sqlite for mapping.  Set $file to an SQLite DSN.
YKmap:  Add support for password+OTP validation to make 2fa.  In FreeRADIUS's config, authentication section, you'll need an Auth-Type Perl{} block.  Passwords are either the first public_id or the 'crypt_password' sqlite column. (these are the output of crypt() )
YKmap:  Plain-text file support not tested yet. SQLite works as expected.

ykmap.sql: This is the schema.

rlm_yubico.pl: Remove dependency on AnyEvent::Yubico.  Fails to validate OTPs on Debian Wheezy after several successful or unsuccessful attempts.  Probably a thread-related issue.
rlm_yubico.pl: Remove dependency on Crypt::CBC.  Use of Carp causes namespace issue on Debian Wheezy. (e.g. Undefined function Carp::authorize)
rlm_yubico.pl: Reject authorization instead of do challenge-response if user fails to enter OTP.  Behavior is consistent with normal login process; removes dependency on Crypt::CBC.
rlm_yubico.pl: Use HTTP::Tiny and code/logic from AnyEvent::Yubico to validate OTPs.  This is a little slower, as it queries validation servers in series instead of parallel.  On the flip side, it works.
rlm_yubico.pl: Use Crypt::OpenSSL::Random for generating nonces.  UUID::Tiny is not cryptographically strong.
rlm_yubico.pl: Reword some log messages and log at a higher level so information valuable for intrusion detection and troubleshooting config is available without running in debug mode.