add Vagrant support

[abicorios]

The folder /home/admin/conf/web/ has empty files after install Vesta on pure Vagrant systems (cenos/7, debian/stretch64, ubuntu/bionic64) if it is used option config.vm.network "private_network" or config.vm.network "public_network" in the Vagrantfile. This patch fix it.
My initial test on Ubuntu host and Centos host:
Install VirtualBox
Install last Vagrant

cd
mkdir vesta
cd vesta
vagrant init centos/7
#uncomment config.vm.network "private_network" or config.vm.network "public_network" option in Vagrantfile
vagrant up
vagrant ssh
curl -O http://vestacp.com/pub/vst-install.sh
sudo bash vst-install.sh
hostname -I # to see right ip address

For exit:

exit
vagrant halt
vagrant destroy # only if need delete virtual machine