Hello all,

here is a patch which adds doc, error strings and return a new CURLE_SSL_CACERT_BADFILE error which tells that the CA cert problem is linked to a bad/missing CACERT file, not a missing certificate which would validate server certificate.
it helps users understand why a certificate problem happens.

the test case 305 was modified to accept error 77 (CURLE_SSL_CACERT_BADFILE) in place of 60, because it is actually the case [the test case was tested against OpenSSL, GnuTLS was updated accordingly so it should work, but i don't have it here to test]

Regards
Armel Asselin