title: Couldn't find method exclude() in react-native-google-signin
body: <p>I am a newbie so I need help about my gradle dependencies when using <code>react-native-google-signin</code> library and I'm not sure if I missed it or just misstyped something because I have followed step by step from this repo:
  <a href="https://github.com/devfd/react-native-google-signin/blob/master/android-guide.md" rel="noreferrer">https://github.com/devfd/react-native-google-signin/blob/master/android-guide.md</a>, but my build.gradle script cannot compile. </p>
  
  <p>This is my dependencies in <code>app/build.gradle</code> :</p>
  
  <pre><code>dependencies {
      compile project(':react-native-maps')
      compile project(':react-native-fetch-blob')
      compile project(':react-native-fbsdk')
      compile project(':react-native-oauth')
      compile project(':react-native-linear-gradient')
      compile project(':react-native-fcm')
      compile project(':react-native-device-info')
      compile 'com.google.firebase:firebase-core:10.0.1'
      compile fileTree(include: ['*.jar'], dir: 'libs')
      compile 'com.android.support:appcompat-v7:24.0.1'
      compile 'com.facebook.react:react-native:+'
      // From react-native-sign-in
      compile project(':react-native-google-signin'){
          exclude group: "com.google.android.gms"
      }
      compile 'com.google.android.gms:play-services-auth:9.2.1'
  
      compile('com.crashlytics.sdk.android:crashlytics:2.6.6@aar') {
          transitive = true;
      }
      compile project(':react-native-image-picker')
  }
  </code></pre>
  
  <p>When I run command 'react-native run-android' in my terminal, I encounter this error:</p>
  
  <blockquote>
    <p>Could not find method exclude() for arguments
    [{group=com.google.android.gms}] on project
    ':react-native-google-signin' of type org.gradle.api.Project.</p>
  </blockquote>
  
  <p>So that what I have should work, but I am confused why it doesn't.
  Any idea to fix it?</p>