Fix dependency errors in Android Studio

customtabs/build.gradle

 apply plugin: 'android-library'
 
 dependencies {
-    compile "com.android.support:support-annotations:22.2.0+"
+    compile 'com.android.support:support-annotations:22.2.0+'
+    compile 'com.android.support:support-v4:23.1.1'
 }
 
 android {
     compileSdkVersion 23
     buildToolsVersion "23.0.1"
 
     sourceSets {
         main.manifest.srcFile 'AndroidManifest.xml'
         main.java.srcDirs = ['src']
         main.aidl.srcDirs = ['src']
         main.res.srcDir 'res'
         main.assets.srcDir 'assets'
         main.resources.srcDir 'java'
 
         androidTest.setRoot('tests')
         androidTest.java.srcDir('tests/src/')
     }
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_7
         targetCompatibility JavaVersion.VERSION_1_7
     }
 }