title: Duplicate entry while adding firebaseui and firebase libraries
body: <blockquote>
    <p>check my gradle file for the above error,above error comes while 
          generating signin apk`'</p>
    
    <p>duplicate entry: 
             ``com/google/android/gms/auth/api/signin/zzc.class</p>
  </blockquote>
  
  <p>check my gradle whether it is correct or is there any error in it       </p>
  
  <p>I have facing the issue while generating signin apk
  Is there any error in any dependencies ?</p>
  
  <p>Check my gradle whether it is correct or is there any error in it.</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  
   android {
    compileSdkVersion 24
    buildToolsVersion "24.0.1"
    publishNonDefault true
  
   defaultConfig {
      applicationId "itsolutions.insta"
      minSdkVersion 19
      targetSdkVersion 24
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner 
      "android.support.test.runner.AndroidJUnitRunner"
      multiDexEnabled true
    }
    configurations {
    all*.exclude group: 'com.android.support', module: 'support-v7-appcompat'
    }
  
    packagingOptions {
      exclude 'META-INF/DEPENDENCIES.txt'
      exclude 'META-INF/LICENSE.txt'
      exclude 'META-INF/NOTICE.txt'
      exclude 'META-INF/NOTICE'
      exclude 'META-INF/LICENSE'
      exclude 'META-INF/DEPENDENCIES'
      exclude 'META-INF/notice.txt'
      exclude 'META-INF/license.txt'
      exclude 'META-INF/dependencies.txt'
      exclude 'META-INF/LGPL2.1'
    }
  
  
    buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 
          'proguard-rules.pro'
  
      }
  
    }
  
   }
  
   dependencies {
   androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', 
  {
   exclude group: 'com.android.support', module: 'support-annotations'
   })
  
   compile 'com.android.support:appcompat-v7:24.2.0'
   compile 'com.google.firebase:firebase-auth:11.0.2'
   compile 'com.firebaseui:firebase-ui:1.0.1'
   compile 'com.android.support:design:24.2.0'
   compile 'com.google.firebase:firebase-database:11.0.2'
   compile 'com.google.firebase:firebase-storage:11.0.2'
   compile 'com.android.support:recyclerview-v7:24.2.0'
   compile 'com.android.support:cardview-v7:24.2.0'
   compile 'com.google.firebase:firebase-core:11.0.2'
   compile files('libs/android-support-v7-appcompat.jar')
   }
  
   apply plugin: 'com.google.gms.google-services'
  </code></pre>