title: method "onClick" in butterknife is not work?
body: <p>This is the MainActicity:</p>
  
  <pre><code>package com.example.a10648.demo;
  
  import android.os.Bundle;
  import android.support.v7.app.AppCompatActivity;
  import android.widget.Button;
  import android.widget.Toast;
  
  import butterknife.BindView;
  import butterknife.ButterKnife;
  import butterknife.OnClick;
  
  public class MainActivity extends AppCompatActivity {
  
  
  @BindView(R.id.button)
  Button button;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      ButterKnife.bind(this);
  }
  
  @OnClick(R.id.button)
  public void onClick() {
      Toast.makeText(MainActivity.this,"ok",Toast.LENGTH_SHORT).show();
  }
  }
  </code></pre>
  
  <p>This is the xml  file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context="com.example.a10648.demo.MainActivity"&gt;
  
  &lt;Button
      android:id="@+id/button"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Button!" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>and I have 
  compile 'com.jakewharton:butterknife:8.0.1'<br>
  this is build.gradle in app</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
  compileSdkVersion 23
  buildToolsVersion "23.0.3"
  
  defaultConfig {
      applicationId "com.example.a10648.demo"
      minSdkVersion 18
      targetSdkVersion 23
      versionCode 1
      versionName "1.0"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  }
  
  dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  testCompile 'junit:junit:4.12'
  compile 'com.android.support:appcompat-v7:23.3.0'
  compile 'com.jakewharton:butterknife:8.0.1'
   }
  </code></pre>
  
  <p>the method onClick in bufferknife is not work,
  when I clicked the button ,there is no Toast to appear?
  I don't know why happen like this ?</p>