travis: Bump to golang 1.10

This requires breaking changes in gofmt. It is hilarious that this was
changed. Oh well. This also moves to the latest stable etcd. Lastly,
this changes the `go vet` testing to test by package, since the new go
vet changed how it works and now fails without this change.

lang/structs.go

@@ -1722,10 +1722,10 @@ func (obj *ExprStr) String() string { return fmt.Sprintf("str(%s)", obj.V) }
 // itself.
 func (obj *ExprStr) Interpolate() (interfaces.Expr, error) {
 	pos := &Pos{
-	// column/line number, starting at 1
-	//Column: -1, // TODO
-	//Line: -1, // TODO
-	//Filename: "", // optional source filename, if known
+		// column/line number, starting at 1
+		//Column: -1, // TODO
+		//Line: -1, // TODO
+		//Filename: "", // optional source filename, if known
 	}
 	result, err := InterpolateStr(obj.V, pos)
 	if err != nil {