simplify whisper config condition

Author: iurimatias

lib/blockchain.js

@@ -19,15 +19,10 @@ var Blockchain = function(blockchainConfig, Client) {
     port: this.blockchainConfig.port || 30303,
     nodiscover: this.blockchainConfig.nodiscover || false,
     mine: this.blockchainConfig.mine || false,
-    account: this.blockchainConfig.account || {}
+    account: this.blockchainConfig.account || {},
+    whisper: (this.blockchainConfig.whisper === undefined) || this.blockchainConfig.whisper
   };
 
-  if (this.blockchainConfig.whisper === false) {
-    this.config.whisper = false;
-  } else {
-    this.config.whisper = (this.blockchainConfig.whisper || true);
-  }
-
   this.client = new Client({config: this.config});
 };