Fix the broken _duo_preauth refactor.

The BSON object we're using needs to be the same across all of these functions,
not a random uninitialized object.
Merge pull request #8 from nelhage/fix-refactor

Fix the broken _duo_preauth refactor.
pasto
credit nelhage
if the conversation prompt function fails, abort further auth attempts
require Duo API host to be specified
update duo_unix docs
remove api-eval hostnames
load CA cert from memory (for OpenSSL libcurl), or from $sysconfdir/duo.crt (for all others). also, lookup IP of outbound interface for our API host, which might not be IPv4... eventually ;-)
load CA cert from memory (for OpenSSL libcurl), or from $sysconfdir/duo.crt (for all others). also, lookup IP of outbound interface for our API host, which might not be IPv4... eventually ;-)
update for new duo_open() cafile argument
update for new duo_open() cafile argument, add -h option to specify remote client host (like login(1))
doc changes
bump version for release
remove old docs
remove old docs
handle empty BSON response
add tests
whack unused files
cleanup _log(), add debug flag to output to stderr