added maker add/remove events to staking pools

contracts/staking/contracts/src/core/MixinStakingPool.sol

@@ -111,7 +111,7 @@ contract MixinStakingPool is
         _createPoolInRewardVault(poolId, operatorShare);
 
         // notify
-        emit PoolCreated(poolId, operatorAddress, operatorShare);
+        emit StakingPoolCreated(poolId, operatorAddress, operatorShare);
         return poolId;
     }
 
@@ -290,6 +290,12 @@ contract MixinStakingPool is
         );
         poolIdByMakerAddress[makerAddress] = poolId;
         makerAddressesByPoolId[poolId].push(makerAddress);
+
+        // notify
+        emit MakerAddedToStakingPool(
+            poolId,
+            makerAddress
+        );
     }
 
     /// @dev Unrecords a maker for a pool.
@@ -330,5 +336,11 @@ contract MixinStakingPool is
 
         // reset the pool id assigned to the maker.
         poolIdByMakerAddress[makerAddress] = NIL_MAKER_ID;
+
+        // notify
+        emit MakerRemovedFromStakingPool(
+            poolId,
+            makerAddress
+        );
     }
 }

contracts/staking/contracts/src/interfaces/IStakingEvents.sol

@@ -13,12 +13,6 @@ interface IStakingEvents {
         uint256 amount
     );
 
-    event PoolCreated(
-        bytes32 poolId,
-        address operatorAddress,
-        uint8 operatorShare
-    );
-
     event ExchangeAdded(
         address exchangeAddress
     );
@@ -68,4 +62,31 @@ interface IStakingEvents {
     event OwnershipTransferred(
         address newOwner
     );
+
+
+    /// @dev Emitted by MixinStakingPool when a new pool is created.
+    /// @param poolId Unique id generated for pool.
+    /// @param operatorAddress Address of creator/operator of pool.
+    /// @param operatorShare The share of rewards given to the operator.
+    event StakingPoolCreated(
+        bytes32 poolId,
+        address operatorAddress,
+        uint8 operatorShare
+    );
+
+    /// @dev Emitted by MixinStakingPool when a new maker is added to a pool.
+    /// @param poolId Unique id of pool.
+    /// @param makerAddress Adress of maker added to pool.
+    event MakerAddedToStakingPool(
+        bytes32 poolId,
+        address makerAddress
+    );
+
+    /// @dev Emitted by MixinStakingPool when a maker is removed from a pool.
+    /// @param poolId Unique id of pool.
+    /// @param makerAddress Adress of maker added to pool.
+    event MakerRemovedFromStakingPool(
+        bytes32 poolId,
+        address makerAddress
+    );
 }