Tweaks to Travis-CI config
Tweaks to Travis-CI config

NicWayand/xray,pydata/xarray,markelg/xray,shoyer/xray,jcmgray/xarray,hetland/xray,markelg/xray,petercable/xray,drewokane/xray,rabernat/xray,clarkfitzg/xray,cpaulik/xray,pydata/xarray,jhamman/xray,xray/xray,jhamman/xarray,chunweiyuan/xarray,cpaulik/xray,pydata/xarray,rabernat/xray,hetland/xray,markelg/xray,shoyer/xarray,shoyer/xarray,kjordahl/xray,clarkfitzg/xray,jhamman/xarray,kjordahl/xray,jhamman/xarray