Added multischema support (works on databases that support trough Connection.getMetaData().getSchemas())

grails.plugin.databasemigration.multiSchema = false // enable
grails.plugin.databasemigration.multiSchemaPattern = 'test_.*'	// pattern to match with schema
grails.plugin.databasemigration.multiSchemaList = ['test_1', 'test_2', 'test_3'] // schema list