remove process.exit when no callback passed and remove optimist help when in module mode

Fixes #516

Author: wzrdtales

api.js

@@ -24,6 +24,9 @@ function dbmigrate (plugins, isModule, options, callback) {
     onComplete: onComplete,
     migrationProtocol: 1
   };
+  if (typeof isModule !== 'function') {
+    this.internals.isModule = isModule;
+  }
   var internals = this.internals;
 
   this.internals.plugins = load('fn/plugin')(plugins);

lib/commands/create-migration.js

@@ -31,8 +31,15 @@ function executeCreateMigration (internals, config, callback) {
 
   if (internals.argv._.length === 0) {
     log.error("'migrationName' is required.");
-    optimist.showHelp();
-    process.exit(1);
+    if (!internals.isModule) {
+      optimist.showHelp();
+    }
+
+    if (typeof callback !== 'function') {
+      process.exit(1);
+    } else {
+      return callback(new Error("'migrationName' is required."));
+    }
   }
 
   createMigrationDir(migrationsDir, function (err) {
@@ -41,7 +48,11 @@ function executeCreateMigration (internals, config, callback) {
 
     if (err) {
       log.error('Failed to create migration directory at ', migrationsDir, err);
-      process.exit(1);
+      if (typeof callback !== 'function') {
+        process.exit(1);
+      } else {
+        return callback(new Error('Failed to create migration directory.'));
+      }
     }
 
     internals.argv.title = internals.argv._.shift();
@@ -88,7 +99,7 @@ function executeCreateMigration (internals, config, callback) {
           createSqlFiles(internals, config, callback);
         } else {
           if (typeof callback === 'function') {
-            callback();
+            return callback();
           }
         }
       }