Added test-projects to solution and upgraded build to latest tools.

build.gradle

@@ -2,6 +2,7 @@
 buildscript {
     repositories {
         jcenter()
+        maven { url 'http://repo1.maven.org/maven2' }
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.1.0'
@@ -11,5 +12,10 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven { url 'http://repo1.maven.org/maven2' }
     }
 }
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}