Added removeHandler method.

ethereumj-core-android/src/main/java/org/ethereum/android/service/ServiceConnector.java

@@ -144,4 +144,9 @@ public class ServiceConnector {
         }
     }
 
+    public void removeHandler(ConnectorHandler handler) {
+
+        handlers.remove(handler);
+    }
+
 }

ethereumj-core/src/main/java/org/ethereum/core/Block.java

@@ -54,7 +54,9 @@ public class Block {
     /* Constructors */
 
     public Block(byte[] rawData) {
-        logger.debug("new from [" + Hex.toHexString(rawData) + "]");
+        if (rawData != null) {
+            logger.debug("new from [" + Hex.toHexString(rawData) + "]");
+        }
         this.rlpEncoded = rawData;
     }