make http return code for mismatched rules configurable

Signed-off-by: Mathias Merscher <Mathias.Merscher@dg-i.net>

test/hooks.json.tmpl

@@ -4,6 +4,7 @@
     "execute-command": "{{ .Hookecho }}",
     "command-working-directory": "/",
     "include-command-output-in-response": true,
+    "trigger-rule-mismatch-code": 400,
     "pass-environment-to-command":
     [
       {
@@ -59,6 +60,7 @@
     "command-working-directory": "/",
     "include-command-output-in-response": false,
     "response-message": "success",
+    "trigger-rule-mismatch-code": 999,
     "parse-parameters-as-json": [
       {
         "source": "payload",