Add .xsjs and .xsjslib as JavaScript file extension

.xsjs and .xsjslib is used to denote server-side JavaScript files in SAP
HANA XS

lib/linguist/languages.yml

@@ -1095,6 +1095,8 @@ JavaScript:
   - .pac
   - .sjs
   - .ssjs
+  - .xsjs
+  - .xsjslib
   filenames:
   - Jakefile
   interpreters:

samples/JavaScript/helloHanaEndpoint.xsjs

@@ -0,0 +1,24 @@
+/*
+ invoke endpoint by calling in a browser:
+ http://<hanaserveradress>:<xsengineport(usually 8000)>/<path>/<to>/<endpoint>/helloHanaMath.xsjslib?x=4&y=2
+ e.g.:
+ http://192.168.178.20:8000/geekflyer/linguist/helloHanaEndpoint.xsjs?x=4&y=2
+ */
+
+var hanaMath = $.import("./helloHanaMath.xsjslib");
+
+var x = parseFloat($.request.parameters.get("x"));
+var y = parseFloat($.request.parameters.get("y"));
+
+
+var result = hanaMath.multiply(x, y);
+
+var output = {
+    title: "Hello HANA XS - do some simple math",
+    input: {x: x, y: y},
+    result: result
+};
+
+$.response.contentType = "application/json";
+$.response.statusCode = $.net.http.OK;
+$.response.setBody(JSON.stringify(output));

samples/JavaScript/helloHanaMath.xsjslib

@@ -0,0 +1,9 @@
+/* simple hana xs demo library, which can be used by multiple endpoints */
+
+function multiply(x, y) {
+    return x * y;
+}
+
+function add(x, y) {
+    return x + y;
+}