Adding dep files and dependencies.

vendor/github.com/montanaflynn/stats/sum.go

@@ -0,0 +1,18 @@
+package stats
+
+import "math"
+
+// Sum adds all the numbers of a slice together
+func Sum(input Float64Data) (sum float64, err error) {
+
+	if input.Len() == 0 {
+		return math.NaN(), EmptyInput
+	}
+
+	// Add em up
+	for _, n := range input {
+		sum += n
+	}
+
+	return sum, nil
+}