Events added to Secondary (#1425)

* Update contracts/ownership/Secondary.sol

* Update Secondary.sol

* Update Secondary.test.js

* Update Secondary.test.js

* Update Secondary.sol

(cherry picked from commit cbe414864f)

contracts/ownership/Secondary.sol

@@ -7,11 +7,16 @@ pragma solidity ^0.4.24;
 contract Secondary {
   address private _primary;
 
+  event PrimaryTransferred(
+    address recipient
+  );
+
   /**
    * @dev Sets the primary account to the one that is creating the Secondary contract.
    */
   constructor() internal {
     _primary = msg.sender;
+    emit PrimaryTransferred(_primary);
   }
 
   /**
@@ -22,13 +27,20 @@ contract Secondary {
     _;
   }
 
+  /**
+   * @return the address of the primary.
+   */
   function primary() public view returns (address) {
     return _primary;
   }
-
+  
+  /**
+   * @dev Transfers contract to a new primary.
+   * @param recipient The address of new primary. 
+   */
   function transferPrimary(address recipient) public onlyPrimary {
     require(recipient != address(0));
-
     _primary = recipient;
+    emit PrimaryTransferred(_primary);
   }
 }