New SSL policy scripts.

- protocols/ssl/expiring-certs uses time based information from
  certificates to determine if they will expire soon, have already
  expired, or haven't yet become valid.

- protocols/ssl/extract-certs-pem is a script for taking certs off
  the line and converting them to PEM certificates with the openssl
  command line tool then dumping them to a file.

scripts/base/protocols/ssl/main.bro

@@ -35,6 +35,11 @@ export {
 	## (especially with large file transfers).
 	const disable_analyzer_after_detection = T &redef;
 	
+	## The openssl command line utility.  If it's in the path the default
+	## value will work, otherwise a full path string can be supplied for the
+	## utility.
+	const openssl_util = "openssl" &redef;
+	
 	global log_ssl: event(rec: Info);
 	
 	const ports = {