CI job to validate openapi syntax of the definitions

Change-Id: I635814cd5284fbd11586536008e8d2561b4adf5c
Signed-off-by: Michele Carignani <michele.carignani@etsi.org>

.jenkins.sh

+#!/bin/bash
+
+specfiles=$(ls | egrep "^[^.]*.(json|yaml)")
+
+fres=0
+for i in $specfiles ; do
+    echo "-- Validating OpenAPI file $i..."
+    swagger-tools validate $i
+    res=$?
+    fres=$(($fres||$res))
+    echo -e "-- Validator returned $res.\n"
+done
+
+echo "-- Final validator returns $fres."
+exit $fres