Merge pull request #601 from elopio/test/math

test: add tests for max64 and min64 from Math

test/mocks/MathMock.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.4.18;
+
+
+import '../../contracts/math/Math.sol';
+
+
+contract MathMock {
+  uint64 public result;
+
+  function max64(uint64 a, uint64 b) public {
+    result = Math.max64(a, b);
+  }
+
+  function min64(uint64 a, uint64 b) public {
+    result = Math.min64(a, b);
+  }
+}