Update util.js

Because there is only one argument for the method.

I know from lodash 3 to loadash 4 you need to change some `min` to `minBy`, but not all of them should be changed.

lib/util.js

@@ -147,7 +147,7 @@ function buildLayerMatrix(g) {
  * rank(v) >= 0 and at least one node w has rank(w) = 0.
  */
 function normalizeRanks(g) {
-  var min = _.minBy(_.map(g.nodes(), function(v) { return g.node(v).rank; }));
+  var min = _.min(_.map(g.nodes(), function(v) { return g.node(v).rank; }));
   _.forEach(g.nodes(), function(v) {
     var node = g.node(v);
     if (_.has(node, "rank")) {
@@ -158,7 +158,7 @@ function normalizeRanks(g) {
 
 function removeEmptyRanks(g) {
   // Ranks may not start at 0, so we need to offset them
-  var offset = _.minBy(_.map(g.nodes(), function(v) { return g.node(v).rank; }));
+  var offset = _.min(_.map(g.nodes(), function(v) { return g.node(v).rank; }));
 
   var layers = [];
   _.forEach(g.nodes(), function(v) {