Added travis build badge to README.MD
Added travis build badge to README.MD

iGusev/influxdb-php,cnelissen/influxdb-php,influxdata/influxdb-php,eugenegp/influxdb-php,zengzhihai110/influxdb-php,eugenegp/influxdb-php,CentaurWarchief/influxdb-php,influxdb/influxdb-php,influxdata/influxdb-php,influxdb/influxdb-php