Roles now emit events in construction and when renouncing. (#1329)

* release candidate v2.0.0-rc.1

* fix linter error

(cherry picked from commit c12a1c6898)

* Roles now emit events in construction and when renouncing.

contracts/access/roles/CapperRole.sol

@@ -11,7 +11,7 @@ contract CapperRole {
   Roles.Role private cappers;
 
   constructor() public {
-    cappers.add(msg.sender);
+    _addCapper(msg.sender);
   }
 
   modifier onlyCapper() {
@@ -24,12 +24,16 @@ contract CapperRole {
   }
 
   function addCapper(address account) public onlyCapper {
-    cappers.add(account);
-    emit CapperAdded(account);
+    _addCapper(account);
   }
 
   function renounceCapper() public {
-    cappers.remove(msg.sender);
+    _removeCapper(msg.sender);
+  }
+
+  function _addCapper(address account) internal {
+    cappers.add(account);
+    emit CapperAdded(account);
   }
 
   function _removeCapper(address account) internal {

contracts/access/roles/MinterRole.sol

@@ -11,7 +11,7 @@ contract MinterRole {
   Roles.Role private minters;
 
   constructor() public {
-    minters.add(msg.sender);
+    _addMinter(msg.sender);
   }
 
   modifier onlyMinter() {
@@ -24,12 +24,16 @@ contract MinterRole {
   }
 
   function addMinter(address account) public onlyMinter {
-    minters.add(account);
-    emit MinterAdded(account);
+    _addMinter(account);
   }
 
   function renounceMinter() public {
-    minters.remove(msg.sender);
+    _removeMinter(msg.sender);
+  }
+
+  function _addMinter(address account) internal {
+    minters.add(account);
+    emit MinterAdded(account);
   }
 
   function _removeMinter(address account) internal {

contracts/access/roles/PauserRole.sol

@@ -11,7 +11,7 @@ contract PauserRole {
   Roles.Role private pausers;
 
   constructor() public {
-    pausers.add(msg.sender);
+    _addPauser(msg.sender);
   }
 
   modifier onlyPauser() {
@@ -24,12 +24,16 @@ contract PauserRole {
   }
 
   function addPauser(address account) public onlyPauser {
-    pausers.add(account);
-    emit PauserAdded(account);
+    _addPauser(account);
   }
 
   function renouncePauser() public {
-    pausers.remove(msg.sender);
+    _removePauser(msg.sender);
+  }
+
+  function _addPauser(address account) internal {
+    pausers.add(account);
+    emit PauserAdded(account);
   }
 
   function _removePauser(address account) internal {

contracts/access/roles/SignerRole.sol

@@ -11,7 +11,7 @@ contract SignerRole {
   Roles.Role private signers;
 
   constructor() public {
-    signers.add(msg.sender);
+    _addSigner(msg.sender);
   }
 
   modifier onlySigner() {
@@ -24,12 +24,16 @@ contract SignerRole {
   }
 
   function addSigner(address account) public onlySigner {
-    signers.add(account);
-    emit SignerAdded(account);
+    _addSigner(account);
   }
 
   function renounceSigner() public {
-    signers.remove(msg.sender);
+    _removeSigner(msg.sender);
+  }
+
+  function _addSigner(address account) internal {
+    signers.add(account);
+    emit SignerAdded(account);
   }
 
   function _removeSigner(address account) internal {