(ids) add test ruleset for suricata

enable the opnsense test ruleset and try to download the eicar virus:

http://www.eicar.org/download/eicar.com.txt

it should block (over http)

closes https://github.com/opnsense/core/issues/884

src/opnsense/scripts/suricata/metadata/rules/opnsense.xml

+<?xml version="1.0"?>
+<ruleset documentation_url="http://docs.opnsense.org/">
+    <location url="https://rulesets.opnsense.org/suricata/" prefix="OPNsense"/>
+    <files>
+        <file description="test rules">opnsense.test.rules</file>
+    </files>
+</ruleset>