Update Vagrant private IP address, fix issue #2062 (#2064)

CONTRIBUTING.md

@@ -20,9 +20,9 @@ _If you're seeing an error message about your *IP address being listed in the Sp
 
 ### Modifying your `hosts` file
 
-After a while, Mail-in-a-Box will be available at `192.168.50.4` (unless you changed that in your `Vagrantfile`). To be able to use the web-based bits, we recommend to add a hostname to your `hosts` file:
+After a while, Mail-in-a-Box will be available at `192.168.56.4` (unless you changed that in your `Vagrantfile`). To be able to use the web-based bits, we recommend to add a hostname to your `hosts` file:
 
-    $ echo "192.168.50.4 mailinabox.lan" | sudo tee -a /etc/hosts
+    $ echo "192.168.56.4 mailinabox.lan" | sudo tee -a /etc/hosts
 
 You should now be able to navigate to https://mailinabox.lan/admin using your browser. There should be an initial admin user with the name `me@mailinabox.lan` and the password `12345678`.
 

Vagrantfile

@@ -9,7 +9,7 @@ Vagrant.configure("2") do |config|
   # the machine's box will let anyone log into it. So instead we'll put the
   # machine on a private network.
   config.vm.hostname = "mailinabox.lan"
-  config.vm.network "private_network", ip: "192.168.50.4"
+  config.vm.network "private_network", ip: "192.168.56.4"
 
   config.vm.provision :shell, :inline => <<-SH
     # Set environment variables so that the setup script does