vagrant CHANGE comment vagrant URL replacement

The line with URL replacement causes another error in newer vagrant versions,
so it was commented and added a note into README for users of older versions.
diff --git a/vagrant/OpenSUSE/Vagrantfile b/vagrant/OpenSUSE/Vagrantfile
index cc1853c..f94d02a 100644
--- a/vagrant/OpenSUSE/Vagrantfile
+++ b/vagrant/OpenSUSE/Vagrantfile
@@ -92,7 +92,8 @@
 /usr/local/bin/netopeer2-server -d > netopeer2.log 2>&1 &
 SCRIPT
 
-Vagrant::DEFAULT_SERVER_URL.replace('https://vagrantcloud.com')
+# uncomment the following line for vagrant < 2.0.0
+# Vagrant::DEFAULT_SERVER_URL.replace('https://vagrantcloud.com')
 Vagrant.configure("2") do |config|
   config.vm.provider :virtualbox do |vb|
     vb.customize ["modifyvm", :id, "--memory", "2048"]
diff --git a/vagrant/README.md b/vagrant/README.md
index 0944ebe..31e9371 100644
--- a/vagrant/README.md
+++ b/vagrant/README.md
@@ -13,6 +13,9 @@
 - [Virtualbox](https://www.virtualbox.org/wiki/Downloads)
 - [Vagrant](http://www.vagrantup.com/downloads.html)
 
+In case you are using vagrant version < 2.0.0, you are supposed to uncomment
+a single line in Vagrant file to correct vagrant server URL.
+
 Running Netopeer2GUI in Vagrant
 -------------------------------
 
diff --git a/vagrant/Ubuntu-release/Vagrantfile b/vagrant/Ubuntu-release/Vagrantfile
index 613c51f..376102e 100644
--- a/vagrant/Ubuntu-release/Vagrantfile
+++ b/vagrant/Ubuntu-release/Vagrantfile
@@ -35,7 +35,8 @@
 service apache2 restart
 SCRIPT
 
-Vagrant::DEFAULT_SERVER_URL.replace('https://vagrantcloud.com')
+# uncomment the following line for vagrant < 2.0.0
+# Vagrant::DEFAULT_SERVER_URL.replace('https://vagrantcloud.com')
 Vagrant.configure("2") do |config|
   config.vm.provider :virtualbox do |vb|
     vb.customize ["modifyvm", :id, "--memory", "1024"]
diff --git a/vagrant/Ubuntu/Vagrantfile b/vagrant/Ubuntu/Vagrantfile
index d64b577..5c97296 100644
--- a/vagrant/Ubuntu/Vagrantfile
+++ b/vagrant/Ubuntu/Vagrantfile
@@ -104,7 +104,8 @@
 /usr/local/bin/netopeer2-server -d > netopeer2.log 2>&1 &
 SCRIPT
 
-Vagrant::DEFAULT_SERVER_URL.replace('https://vagrantcloud.com')
+# uncomment the following line for vagrant < 2.0.0
+#Vagrant::DEFAULT_SERVER_URL.replace('https://vagrantcloud.com')
 Vagrant.configure("2") do |config|
   config.vm.provider :virtualbox do |vb|
     vb.customize ["modifyvm", :id, "--memory", "2048"]