Add ECRecoveryMock contract

contracts/mocks/ECRecoveryMock.sol

@@ -0,0 +1,16 @@
+pragma solidity ^0.4.18;
+
+
+import '../ECRecovery.sol';
+
+
+contract ECRecoveryMock {
+  using ECRecovery for bytes32;
+
+  address public addrRecovered;
+
+  function recover(bytes32 hash, bytes sig) public returns (address) {
+    addrRecovered = hash.recover(sig);
+  }
+
+}