title: Pdf Viewer implementation causes Gradle project sync is failed
body: <p>I created a project on Android Studio 2.3.3 and added pdf viewer as below:</p>
  
  <pre><code>compile 'com.github.barteksc:android-pdf-viewer:2.0.3'
  </code></pre>
  
  <p>I can build the project without error and I can display pdf file.</p>
  
  <p>Now I am trying to add this library to a new project that I created on Android studio 3.0.1 as below, Gradle project sync is failed.</p>
  
  <pre><code>implementation 'com.github.barteksc:android-pdf-viewer:2.0.3'
  </code></pre>
  
  <p>I am getting this errors;</p>
  
  <blockquote>
    <p>Error:Unable to resolve dependency for ':app@debug/compileClasspath':
    Could not resolve com.github.barteksc:android-pdf-viewer:2.0.3.</p>
  </blockquote>
  
  <p>My gradle.build;</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 26
      defaultConfig {
          applicationId "test.com.pdfviewer"
          minSdkVersion 21
          targetSdkVersion 26
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation fileTree(include: ['*.jar'], dir: 'libs')
      implementation 'com.android.support:appcompat-v7:26.1.0'
      implementation 'com.android.support.constraint:constraint-layout:1.0.2'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.1'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
      implementation 'com.github.barteksc:android-pdf-viewer:2.0.3'
  }
  </code></pre>