add whenNotPaused modifier to all of PausableToken functions that modify it's state. Fix #401

contracts/token/PausableToken.sol

@@ -11,11 +11,23 @@ import '../lifecycle/Pausable.sol';
 
 contract PausableToken is StandardToken, Pausable {
 
-  function transfer(address _to, uint256 _value) whenNotPaused public returns (bool) {
+  function transfer(address _to, uint256 _value) public whenNotPaused returns (bool) {
     return super.transfer(_to, _value);
   }
 
-  function transferFrom(address _from, address _to, uint256 _value) whenNotPaused public returns (bool) {
+  function transferFrom(address _from, address _to, uint256 _value) public whenNotPaused returns (bool) {
     return super.transferFrom(_from, _to, _value);
   }
+
+  function approve(address _spender, uint256 _value) public whenNotPaused returns (bool) {
+    return super.approve(_spender, _value);
+  }
+
+  function increaseApproval(address _spender, uint _addedValue) public whenNotPaused returns (bool success) {
+    return super.increaseApproval(_spender, _addedValue);
+  }
+
+  function decreaseApproval(address _spender, uint _subtractedValue) public whenNotPaused returns (bool success) {
+    return super.decreaseApproval(_spender, _subtractedValue);
+  }
 }