wrap undo/migrate in an authenticate call and log error

bin/sequelize

@@ -229,6 +229,7 @@ if (program.migrate || program.undo) {
       migratorOptions = _.merge(migratorOptions, { filesFilter: /\.js$|\.coffee$/ })
     }
 
+    sequelize.authenticate().success(function () {
       var migrator = sequelize.getMigrator(migratorOptions)
 
       if (program.undo) {
@@ -250,6 +251,9 @@ if (program.migrate || program.undo) {
           process.exit(0)
         })
       }
+    }).error(function (err) {
+      console.error("Unable to connect to database: "+err)
+    })
   } else {
     console.log('Cannot find "' + configuration.configFile + '". Have you run "sequelize --init"?')
     process.exit(1)