Add DeleteWebhook request

Author: pengrad

src/main/java/com/pengrad/telegrambot/request/DeleteWebhook.java

@@ -0,0 +1,14 @@
+package com.pengrad.telegrambot.request;
+
+import com.pengrad.telegrambot.response.BaseResponse;
+
+/**
+ * Stas Parshin
+ * 07 December 2016
+ */
+public class DeleteWebhook extends BaseRequest<DeleteWebhook, BaseResponse> {
+
+    public DeleteWebhook() {
+        super(BaseResponse.class);
+    }
+}

src/test/java/com/pengrad/telegrambot/TelegramBotTest.java

@@ -242,6 +242,15 @@ public void setWebhook() {
                         .allowedUpdates("message", "callback_query")
         );
         assertTrue(response.isOk());
+
+        response = bot.execute(new SetWebhook());
+        assertTrue(response.isOk());
+    }
+
+    @Test
+    public void deleteWebhook() {
+        BaseResponse response = bot.execute(new DeleteWebhook());
+        assertTrue(response.isOk());
     }
 
     @Test