Adds HUP support for audit log files to close and reopen. This makes it
much easier to deal with normal log rotation methods.
As part of testing this I noticed that HUP and other items that come out
of command/server.go are going to stderr, which is where our normal log
lines go. This isn't so much problematic with our normal output but as
we officially move to supporting other formats this can cause
interleaving issues, so I moved those to stdout instead.
with a new endpoint '/sys/audit-hash', which returns the given input
string hashed with the given audit backend's hash function and salt
(currently, always HMAC-SHA256 and a backend-specific salt).
In the process of adding the HTTP handler, this also removes the custom
HTTP handlers for the other audit endpoints, which were simply
forwarding to the logical system backend. This means that the various
audit functions will now redirect correctly from a standby to master.
(Tests all pass.)
Fixes#784
Brian Kassouf