Android compile fix

android/build.gradle

@@ -1,12 +1,16 @@
 apply plugin: 'com.android.library'
 
+def DEFAULT_COMPILE_SDK_VERSION             = 25
+def DEFAULT_BUILD_TOOLS_VERSION             = "25.0.3"
+def DEFAULT_TARGET_SDK_VERSION              = 25
+
 android {
-    compileSdkVersion rootProject.ext.compileSdkVersion
-    buildToolsVersion rootProject.ext.buildToolsVersion
+    compileSdkVersion project.hasProperty('compileSdkVersion') ? project.compileSdkVersion : DEFAULT_COMPILE_SDK_VERSION
+    buildToolsVersion project.hasProperty('buildToolsVersion') ? project.buildToolsVersion : DEFAULT_BUILD_TOOLS_VERSION
 
     defaultConfig {
-        minSdkVersion rootProject.ext.minSdkVersion
-        targetSdkVersion rootProject.ext.targetSdkVersion
+        minSdkVersion 16
+        targetSdkVersion project.hasProperty('targetSdkVersion') ? project.targetSdkVersion : DEFAULT_TARGET_SDK_VERSION
         versionCode 1
         versionName "1.0"