Allow clear-text traffic (sync with http://) explicitly for Android 9

import android.annotation.SuppressLint

import android.app.Dialog

import android.content.ClipData

import android.content.ClipboardManager

import android.content.Context

import android.net.Uri

import android.os.Bundle

import android.support.v4.app.DialogFragment

import android.support.v7.app.AlertDialog

import android.widget.Toast

import at.bitfire.davdroid.R

import at.bitfire.davdroid.model.CollectionInfo

import kotlinx.android.synthetic.main.collection_properties.view.*

  -->

<network-security-config>

    <base-config>

    <base-config cleartextTrafficPermitted="true">

        <trust-anchors>

            <certificates src="system"/>

            <certificates src="user"/>