Added a schema for input parameters to Pass class

schema.js

@@ -0,0 +1,39 @@
+const Joi = require("joi");
+
+const schema = Joi.object().keys({
+	modelDir: Joi.string(),
+	modelName: Joi.string(),
+	certificates: Joi.object().keys({
+		dir: Joi.string(),
+		wwdr: Joi.string(),
+		signerCert: Joi.string(),
+		signerKey: Joi.object().keys({
+			keyFile: Joi.string(),
+			passphrase: Joi.string(),
+		})
+	}),
+	handlers: Joi.object().keys({
+		barcode: Joi.func(),
+		serialNumber: Joi.func()
+	}),
+	overrides: Joi.object()
+});
+
+const requiredSchema = schema.requiredKeys(
+	"",
+	"modelDir",
+	"certificates",
+	"certificates.dir",
+	"certificates.wwdr",
+	"certificates.signerCert",
+	"certificates.signerKey",
+	"certificates.signerKey.keyFile",
+	"certificates.signerKey.passphrase"
+);
+
+module.exports = {
+	validate: (opts) => {
+		let validation = Joi.validate(opts, requiredSchema);
+		return !validation.error;
+	}
+};