fix for grails#157

when constructing the sessionFactory bean name for a secondary dataSource, just append the suffix, not the complete dataSource bean name (i.e. sessionFactory_another instead of sessionFactory_dataSource_another)

src/main/groovy/org/grails/plugins/databasemigration/command/ApplicationContextDatabaseMigrationCommand.groovy

@@ -82,7 +82,7 @@ trait ApplicationContextDatabaseMigrationCommand implements DatabaseMigrationCom
  String dataSourceName = getDataSourceName(dataSource)
  String sessionFactoryName = "sessionFactory"
  if (!isDefaultDataSource(dataSource)) {
- sessionFactoryName = sessionFactoryName + '_' + dataSourceName
+ sessionFactoryName = sessionFactoryName + '_' + dataSource
  }
 
  def serviceRegistry = applicationContext.getBean(sessionFactoryName, SessionFactoryImplementor).serviceRegistry.parentServiceRegistry