Bug: UTF8 string on Countryname

[lucasperin]

Issuing certificate with Countryname encoded as UTF8 is not allowed, according to RFC 5280.

• Create CSR with no countryname (other fields should be UTF8 and openssl version >= 1.0.1)
• Add some countryname using certificatebuilder::alterSubject
• Issue certificate

My guess is that alterSubject is not taking countryname into account. We should fix the bug ASAP, however, the best solution would be to rework RDNSequence so that the internal objects are not stored as strings. The wrapper library shouldn't interfere with the underlying library.