Fixed Proguard settings (#88)

* Issue #86 - Deleted a setting for DexGuard

example/build.gradle

@@ -29,6 +29,8 @@ android {
       debuggable false
       zipAlignEnabled true
       signingConfig signingConfigs.release
+      minifyEnabled true
+      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
     }
   }
 }