[#2599] Add a utility for generating the CSS files

Requires the less npm package to be installed. This should eventually
be moved into a paster command.

Usage:

    $ npm install less
    $ ./bin/less                # Works in development
    $ ENV=production ./bin/less # Generate production file.

bin/less

@@ -0,0 +1,38 @@
+#!/usr/bin/env node
+
+var fs = require('fs'),
+    path = require('path'),
+    exec = require('child_process').exec,
+    watch = path.join(__dirname, '..', 'ckan', 'public', 'base', 'less'),
+    debug = process.env.ENV !== 'production';
+
+function now() {
+  return new Date().toISOString().replace('T', ' ').substr(0, 19);
+}
+
+function compile(event, filename) {
+  var start = Date.now(),
+      filename = 'main.css';
+
+  if (debug) {
+    filename = 'main.debug.css';
+  }
+
+  exec('`npm bin`/lessc ckan/public/base/less/main.less > ckan/public/base/css/' + filename, function (err, stdout, stderr) {
+    var duration = Date.now() - start;
+
+    if (err) {
+      console.log('An error occurred running the less command:');
+      console.log(err.message);
+    }
+    else if (stderr || stdout) {
+      console.log(stdout, stderr);
+    } else {
+      console.log('[%s] recompiled ' + filename + ' in %sms', now(), duration);
+    }
+  });
+}
+
+console.log('Watching %s', watch);
+fs.watch(watch, compile);
+compile();