Add BlockCommandSender for Command block

src/main/java/org/bukkit/command/BlockCommandSender.java

@@ -0,0 +1,12 @@
+package org.bukkit.command;
+
+import org.bukkit.block.Block;
+
+public interface BlockCommandSender extends CommandSender {
+    /**
+     * Returns the block this command sender belongs to
+     *
+     * @return Block for the command sender
+     */
+    public Block getBlock();
+}