Merge remote-tracking branch 'origin/topic/seth/dhcp-update'

* origin/topic/seth/dhcp-update:
  Rework to the DHCP analyzer.
  First step of DHCP analyzer rearchitecture.
  Add .btest scripts for dhck_ack and dhcp_discover messages verifying that new options are correctly reported in dhcp.log records.
  Extend DHCP protocol analyzer with new options.

BIT-1924 #merged

Additional changes:

* Removed known-hosts.bro as the only thing populating its table was
  the already-removed known-hosts-and-devices.bro.  So a
  known_devices.log will no longer be generated.

* In dhcp-options.pac, the process_relay_agent_inf_option had a memleak
  and also process_auto_proxy_config_option looked like it accessed one
  byte past the end of the available bytestring, so fixed those.

CHANGES

@@ -1,4 +1,22 @@
 
+2.5-544 | 2018-05-01 17:57:15 -0500
+
+  * Rewrite the DHCP analyzer and accompanying script-layer API.
+    (Valerio G, Corelight)
+
+     * Reduced all DHCP events into a single dhcp_message event.
+       (removed legacy events since they weren't widely used anyway)
+     - Support many more DHCP options.
+
+     - DHCP log is completely reworked and now represents DHCP sessions
+       based on the transaction ID (and works on clusters).
+
+     - Removed the known-devices-and-hostnames.bro and known-devices.bro
+       scripts since it's generally less relevant now with the updated log.
+
+  * Change include directory search order to better support --with-openssl.
+    (Johanna Amann)
+
 2.5-535 | 2018-04-30 16:22:30 -0500
 
   * Improve how coverage unit tests handle name of build dir (Corelight)