Update reference.config

Updated reference.config to match ET Open reference.config found here: 
https://rules.emergingthreats.net/open/suricata/reference.config

Due to startup error shown here:
root@xxxxxxx01:/etc/suricata/rules# /usr/bin/suricata -c /etc/suricata/suricata.yaml --pidfile /var/run/suricata.pid --af-packet
23/12/2014 -- 22:07:56 - <Error> - [ERRCODE: SC_ERR_REFERENCE_UNKNOWN(150)] - unknown reference key "osvdb". Supported keys are defined in reference.config file.  Please have a look at the conf param "reference-config-file"
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Killed