Adds a new network_security_config to allow custom CAs installed by user. This is needed for Android 7+, see https://android-developers.googleblog.com/2016/07/changes-to-trusted-certificate.html.

app/src/main/AndroidManifest.xml

@@ -9,7 +9,8 @@
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
-        android:theme="@style/AppTheme">
+        android:theme="@style/AppTheme"
+        android:networkSecurityConfig=”@xml/network_security_config”>
 
         <activity
             android:name=".MainActivity"