better error handling for custom langauge files

src/plugins.js

@@ -262,8 +262,15 @@ var fs = require('fs'),
 
 							async.each(languages, function(pathToLang, next) {
 								fs.readFile(pathToLang, function(err, file) {
+									try {
+										var json = JSON.parse(file.toString());	
+									} catch (err) {
+										winston.error('[plugins] Unable to parse custom language file: ' + pathToLang + '\r\n' + err.stack);
+										return next(err);
+									}
+
 									arr.push({
-										file: JSON.parse(file.toString()),
+										file: json,
 										route: pathToLang.replace(pathToFolder, '')
 									});