Add example js file for csv output

osmjs/js/osm2csv.js

@@ -0,0 +1,20 @@
+/*
+
+  Osmium Javascript Example
+
+  osm2csv.js
+
+  run with: osmjs -j osm2csv.js OSMFILE
+
+*/
+
+var out = Osmium.Output.CSV.open('out.csv');
+
+Osmium.Callbacks.node = function() {
+    out.print(this.id, this.tags['name'], this.tags['note']);
+}
+
+Osmium.Callbacks.end = function() {
+    out.close();
+}
+