add two travis branch badges 0.6.x vs master
add two travis branch badges 0.6.x vs master

landsurveyorsunited/mapnik-vector-tile,tomhughes/mapnik-vector-tile,tomhughes/mapnik-vector-tile,tomhughes/mapnik-vector-tile,mapbox/mapnik-vector-tile,landsurveyorsunited/mapnik-vector-tile,landsurveyorsunited/mapnik-vector-tile,mapbox/mapnik-vector-tile,mapbox/mapnik-vector-tile,tomhughes/mapnik-vector-tile,mapbox/mapnik-vector-tile