Added retrolambda dependency through gradle plugin.

Author: android10

data/build.gradle

@@ -1,5 +1,19 @@
+buildscript {
+  repositories {
+    mavenCentral()
+  }
+  dependencies {
+    classpath 'me.tatarka:gradle-retrolambda:3.1.0'
+  }
+}
+
+repositories {
+  mavenCentral()
+}
+
 apply plugin: 'com.android.library'
 apply plugin: 'com.neenbedankt.android-apt'
+apply plugin: 'me.tatarka.retrolambda'
 
 android {
   def globalConfiguration = rootProject.extensions.getByName("ext")
@@ -14,8 +28,8 @@ android {
   }
 
   compileOptions {
-    sourceCompatibility JavaVersion.VERSION_1_7
-    targetCompatibility JavaVersion.VERSION_1_7
+    sourceCompatibility JavaVersion.VERSION_1_8
+    targetCompatibility JavaVersion.VERSION_1_8
   }
 
   packagingOptions {