Merge #1267

1267: Update roundcube to 1.4.0 and enable new elastic skin r=hoellen a=hoellen

## What type of PR?
enhancement

## What does this PR do?
This PR brings the new roundcube 1.4.0 release with the new elastic skin.
![grafik](https://user-images.githubusercontent.com/11299996/69373290-c86cd680-0ca3-11ea-8dd5-d76beafc65a6.png)
![grafik](https://user-images.githubusercontent.com/11299996/69373358-e6d2d200-0ca3-11ea-8b92-3b8a528eb6c0.png)


As an idea we could integrate the Mailu logo in a next step to customize the webmail client a bit.

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.


Co-authored-by: hoellen <dev@hoellen.eu>

towncrier/newsfragments/1267.feature

@@ -0,0 +1 @@
+Update roundcube to 1.4.0 and enable the new elastic skin

webmails/roundcube/Dockerfile

@@ -16,7 +16,7 @@ RUN apt-get update && apt-get install -y \
 # Shared layer between nginx, dovecot, postfix, postgresql, rspamd, unbound, rainloop, roundcube
 RUN pip3 install socrate
 
-ENV ROUNDCUBE_URL https://github.com/roundcube/roundcubemail/releases/download/1.3.10/roundcubemail-1.3.10-complete.tar.gz
+ENV ROUNDCUBE_URL https://github.com/roundcube/roundcubemail/releases/download/1.4.1/roundcubemail-1.4.1-complete.tar.gz
 
 RUN apt-get update && apt-get install -y \
       zlib1g-dev libzip4 libzip-dev \

webmails/roundcube/config.inc.php

@@ -34,6 +34,10 @@ $config['smtp_pass'] = '%p';
 $config['managesieve_host'] = $imap;
 $config['managesieve_usetls'] = false;
 
+// Customization settings
+$config['support_url'] = getenv('WEB_ADMIN') ? '../..' . getenv('WEB_ADMIN') : '';
+$config['product_name'] = 'Mailu Webmail';
+
 // We access the IMAP and SMTP servers locally with internal names, SSL
 // will obviously fail but this sounds better than allowing insecure login
 // from the outter world
@@ -48,7 +52,7 @@ $config['smtp_conn_options'] = $ssl_no_check;
 $config['managesieve_conn_options'] = $ssl_no_check;
 
 // skin name: folder from skins/
-$config['skin'] = 'larry';
+$config['skin'] = 'elastic';
 
 // Enigma gpg plugin
 $config['enigma_pgp_homedir'] = '/data/gpg';