Uiautomator: Upgraded uiautomator base classes to Uiauto2

Uiautomator1 has been deprecated, therefore the uiautomation base classes have
been upgraded to use uiautomator2 and the new gradle build system.
Altered to retrieve `package_name` rather than `package` as per the previous commit.

wlauto/external/uiauto/app/build.gradle

@@ -0,0 +1,18 @@
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion 25
+    buildToolsVersion '25.0.3'
+    defaultConfig {
+        minSdkVersion 18
+        targetSdkVersion 25
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+}
+
+dependencies {
+    compile fileTree(include: ['*.jar'], dir: 'libs')
+    compile 'com.android.support.test:runner:0.5'
+    compile 'com.android.support.test:rules:0.5'
+    compile 'com.android.support.test.uiautomator:uiautomator-v18:2.1.2'
+}