Add .cjs (common JS) as a viable extension

Author: Timic3

lib/Common.js

@@ -251,6 +251,8 @@ Common.isConfigFile = function (filename) {
     return 'yaml';
   if (filename.indexOf('.config.js') !== -1)
     return 'js';
+  if (filename.indexOf('.config.cjs') !== -1)
+    return 'js';
   if (filename.indexOf('.config.mjs') !== -1)
     return 'mjs';
   return null;
@@ -283,7 +285,7 @@ Common.parseConfig = function(confObj, filename) {
            filename.indexOf('.yaml') > -1) {
     return yamljs.parse(confObj.toString());
   }
-  else if (filename.indexOf('.config.js') > -1 || filename.indexOf('.config.mjs') > -1) {
+  else if (filename.indexOf('.config.js') > -1 || filename.indexOf('.config.cjs') > -1 || filename.indexOf('.config.mjs') > -1) {
     var confPath = require.resolve(path.resolve(filename));
     delete require.cache[confPath];
     return require(confPath);