prefer build.gradle with Android Plugin as source of package/version/code

These days, the location that overrides all the others is in the android{}
block of the build.gradle file that loads the com.android.application
plugin.  So this should be the preferred place to read these values.

test files GPL licensed: https://github.com/Integreight/1Sheeld-Android-App

tests/source-files/com.integreight.onesheeld/build.gradle

@@ -0,0 +1,16 @@
+// 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:2.3.2'
+        classpath 'com.google.gms:google-services:3.0.0'
+    }
+}
+
+allprojects {
+    repositories {
+        jcenter()
+    }
+}