Use the sdk-manager-plugin for Gradle to bootstrap the Android SDK

This uses an unreleased version of the sdk-manager-plugin built from
sources via JitPack to get some required fixes.

Change-Id: Ia847cb68e28fd753ec64396e90a9b83c5e5fed01
diff --git a/README.md b/README.md
index cdf102d..c42aa1a 100644
--- a/README.md
+++ b/README.md
@@ -126,5 +126,9 @@
 
 * Apache License, Version 2.0
   * [gradle-versions-plugin](https://github.com/ben-manes/gradle-versions-plugin)
+  * [sdk-manager-plugin](https://github.com/JakeWharton/sdk-manager-plugin)
+
+* The MIT License
+  * [jitpack.io](https://github.com/jitpack/jitpack.io)
 
 Compile-time dependencies are listed in the app's help screen.
diff --git a/app/build.gradle b/app/build.gradle
index c080d63..645ce2b 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -1,3 +1,4 @@
+apply plugin: 'android-sdk-manager'
 apply plugin: 'com.android.application'
 
 android {
diff --git a/build.gradle b/build.gradle
index 2f90a61..6b2c1b2 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,11 +5,19 @@
 buildscript {
     repositories {
         jcenter()
+
+        maven {
+            url 'https://jitpack.io'
+        }
     }
+
     dependencies {
         classpath 'com.android.tools.build:gradle:1.5.0'
         classpath 'com.github.ben-manes:gradle-versions-plugin:0.12.0'
 
+        // Use an unreleased version via JitPack.
+        classpath 'com.github.JakeWharton:sdk-manager-plugin:1d29782'
+
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }