minVersion should match react-native (issue #30)

android/build.gradle

@@ -15,7 +15,7 @@ android {
     buildToolsVersion "23.0.1"
 
     defaultConfig {
-        minSdkVersion 18
+        minSdkVersion 16
         targetSdkVersion 23
         versionCode 1
         versionName "1.0"