IP error on vagrant up

[slifty]

When I run vagrant up I get the following error:

The IP address configured for the host-only network is not within the
allowed ranges. Please update the address used to be within the allowed
ranges and run the command again.

  Address: 192.168.33.10
  Ranges: 192.168.56.0/21

Valid ranges can be modified in the /etc/vbox/networks.conf file. For
more information including valid format see:

  https://www.virtualbox.org/manual/ch06.html#network_hostonly

The action needed is pretty self explanatory, but I think we should update our README to mention that this might (will?) be necessary. This StackOverflow answer suggests the "problem" might be due to a recent change in VirtualBox.

We also might want to consider changing the way network / IP is assigned -- I believe vagrant might be smart enough automatically route network traffic from localhost (see the configuration here: https://github.com/OpenTechStrategies/torque-devenv/blob/f36d6156ddbed220c63e0712855a44b0e0008acf/Vagrantfile#L36-L38)