Clean project structure (#320)

example/android/build.gradle

@@ -0,0 +1,24 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+buildscript {
+    repositories {
+        jcenter()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:1.3.1'
+
+        // NOTE: Do not place your application dependencies here; they belong
+        // in the individual module build.gradle files
+    }
+}
+
+allprojects {
+    repositories {
+        mavenLocal()
+        jcenter()
+        maven {
+            // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
+            url "$rootDir/../node_modules/react-native/android"
+        }
+    }
+}