fix ERC20 to conform to standard

contracts/token/BasicToken.sol

@@ -19,10 +19,11 @@ contract BasicToken is ERC20Basic {
   * @param _to The address to transfer to.
   * @param _value The amount to be transferred.
   */
-  function transfer(address _to, uint256 _value) {
+  function transfer(address _to, uint256 _value) returns (bool) {
     balances[msg.sender] = balances[msg.sender].sub(_value);
     balances[_to] = balances[_to].add(_value);
     Transfer(msg.sender, _to, _value);
+    return true;
   }
 
   /**

contracts/token/ERC20.sol

@@ -10,7 +10,7 @@ import './ERC20Basic.sol';
  */
 contract ERC20 is ERC20Basic {
   function allowance(address owner, address spender) constant returns (uint256);
-  function transferFrom(address from, address to, uint256 value);
-  function approve(address spender, uint256 value);
+  function transferFrom(address from, address to, uint256 value) returns (bool);
+  function approve(address spender, uint256 value) returns (bool);
   event Approval(address indexed owner, address indexed spender, uint256 value);
 }

contracts/token/ERC20Basic.sol

@@ -4,11 +4,11 @@ pragma solidity ^0.4.11;
 /**
  * @title ERC20Basic
  * @dev Simpler version of ERC20 interface
- * @dev see https://github.com/ethereum/EIPs/issues/20
+ * @dev see https://github.com/ethereum/EIPs/issues/179
  */
 contract ERC20Basic {
   uint256 public totalSupply;
   function balanceOf(address who) constant returns (uint256);
-  function transfer(address to, uint256 value);
+  function transfer(address to, uint256 value) returns (bool);
   event Transfer(address indexed from, address indexed to, uint256 value);
 }

contracts/token/LimitedTransferToken.sol

@@ -32,8 +32,8 @@ contract LimitedTransferToken is ERC20 {
    * @param _to The address that will recieve the tokens.
    * @param _value The amount of tokens to be transferred.
    */
-  function transfer(address _to, uint256 _value) canTransfer(msg.sender, _value) {
-    super.transfer(_to, _value);
+  function transfer(address _to, uint256 _value) canTransfer(msg.sender, _value) returns (bool) {
+    return super.transfer(_to, _value);
   }
 
   /**
@@ -42,8 +42,8 @@ contract LimitedTransferToken is ERC20 {
   * @param _to The address that will recieve the tokens.
   * @param _value The amount of tokens to be transferred.
   */
-  function transferFrom(address _from, address _to, uint256 _value) canTransfer(_from, _value) {
-    super.transferFrom(_from, _to, _value);
+  function transferFrom(address _from, address _to, uint256 _value) canTransfer(_from, _value) returns (bool) {
+    return super.transferFrom(_from, _to, _value);
   }
 
   /**

contracts/token/PausableToken.sol

@@ -11,11 +11,11 @@ import '../lifecycle/Pausable.sol';
 
 contract PausableToken is StandardToken, Pausable {
 
-  function transfer(address _to, uint _value) whenNotPaused {
-    super.transfer(_to, _value);
+  function transfer(address _to, uint _value) whenNotPaused returns (bool) {
+    return super.transfer(_to, _value);
   }
 
-  function transferFrom(address _from, address _to, uint _value) whenNotPaused {
-    super.transferFrom(_from, _to, _value);
+  function transferFrom(address _from, address _to, uint _value) whenNotPaused returns (bool) {
+    return super.transferFrom(_from, _to, _value);
   }
 }

contracts/token/StandardToken.sol

@@ -23,7 +23,7 @@ contract StandardToken is ERC20, BasicToken {
    * @param _to address The address which you want to transfer to
    * @param _value uint256 the amout of tokens to be transfered
    */
-  function transferFrom(address _from, address _to, uint256 _value) {
+  function transferFrom(address _from, address _to, uint256 _value) returns (bool) {
     var _allowance = allowed[_from][msg.sender];
 
     // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
@@ -33,6 +33,7 @@ contract StandardToken is ERC20, BasicToken {
     balances[_from] = balances[_from].sub(_value);
     allowed[_from][msg.sender] = _allowance.sub(_value);
     Transfer(_from, _to, _value);
+    return true;
   }
 
   /**
@@ -40,7 +41,7 @@ contract StandardToken is ERC20, BasicToken {
    * @param _spender The address which will spend the funds.
    * @param _value The amount of tokens to be spent.
    */
-  function approve(address _spender, uint256 _value) {
+  function approve(address _spender, uint256 _value) returns (bool) {
 
     // To change the approve amount you first have to reduce the addresses`
     //  allowance to zero by calling `approve(_spender, 0)` if it is not
@@ -50,6 +51,7 @@ contract StandardToken is ERC20, BasicToken {
 
     allowed[msg.sender][_spender] = _value;
     Approval(msg.sender, _spender, _value);
+    return true;
   }
 
   /**