allow files with specified extensions to be included in migrator list

lib/migrator.js

@@ -81,6 +81,7 @@ function Migrator(driver, opts) {
   this.driver           = driver;
   this.dir              = (opts.dir || 'migrations');
   this.coffee           = (opts.coffee || false);
+  this.extensions       = (opts.extensions || ['js', this.coffee ? 'coffee' : null]).filter(Boolean);
   this.logger           = (opts.logger || log);
   this.dsl              = new MigrationDsl(this.driver);
   this.migration        = new Migration(this.dsl, this.logger);
@@ -111,12 +112,10 @@ Migrator.prototype.mkdir = function(done) {
 Migrator.prototype.loadModules = function() {
   var self = this;
   return fs.readdirSync(this.dir).filter(function(file) {
-    if (self.coffee) {
-      return file.match(/^\d+.*\.coffee$/);
-    }
-    else {
-      return file.match(/^\d+.*\.js$/);
-    }
+
+    const regex = new RegExp(`^\\d+.*\\.(${ self.extensions.join('|') })$`);
+    return file.match(regex);
+
   }).sort().map(function(file) {
     var mod = require(path.join(process.cwd(), self.dir, file));
     return { file: file, up: mod.up, down: mod.down };

test/helpers.js

@@ -4,7 +4,6 @@ var util   = require('util');
 var path   = require('path');
 var orm    = require('orm');
 var rimraf = require('rimraf');
-var common = module.exports;
 var async  = require('async');