Test with go1.9 in Travis and drop 1.7
Test with go1.9 in Travis and drop 1.7

dcrdata/dcrdata,dcrdata/dcrdata,RogueElement/dcrdata,dcrdata/dcrdata,dcrdata/dcrdata,RogueElement/dcrdata,dcrdata/dcrdata,RogueElement/dcrdata,RogueElement/dcrdata