The certs/ directory contains the TLS certificates required for encrypting
client to server XMPP connections.

The ca-bundle.crt file contains root Certificate Authority (CA) certificates.
These are used to validate certificates presented during TLS handshake
negotiation. The source for this file is the cacert.pem file available
at http://curl.haxx.se/docs/caextract.html.

Any self-signed CA certificate placed in this directory will be considered
a trusted certificate. For example, let's say you're running the wonderland.lit
XMPP server and would like to and verify the ssl cert during TLS.  
The wonderland.lit server hasn't purchased a legitimate TLS certificate
from a CA known in ca-bundle.crt. Instead, they've created a self-signed
certificate and sent it to you. Place the certificate in this directory
with a name of wonderland.lit.crt and it will be trusted. Trusted TLS connections 
from wonderland.lit will now work.

Alternatively, you can purchase a TLS certificate from a CA (e.g. Go Daddy,
VeriSign, etc.) and place it in this directory. This will avoid the hassles
of managing self-signed certificates.