fixed screenshots for themes

src/meta.js

@@ -81,11 +81,21 @@ var utils = require('./../public/src/utils.js'),
 						if (fs.existsSync(config)) {
 							fs.readFile(config, function (err, file) {
 								var configObj = JSON.parse(file.toString());
-								if (!configObj.screenshot) {
+								if (configObj.staticDir && configObj.screenshot) {
+									// Verify that the provided path leads to a file that exists
+									fs.exists(path.join(__dirname, '../node_modules/', configObj.id, configObj.staticDir, configObj.screenshot), function(exists) {
+										if (exists) {
+											configObj.screenshot = path.join('/css/assets/', configObj.screenshot);
+										} else {
+											configObj.screenshot = nconf.get('relative_path') + '/images/themes/default.png';
+										}
+
+										next(err, configObj);
+									});
+								} else {
 									configObj.screenshot = nconf.get('relative_path') + '/images/themes/default.png';
+									next(err, configObj);
 								}
-
-								next(err, configObj);
 							});
 						} else {
 							next();