Include machine name in error message

This will make it easier for folks to debug networking settings.

lib/vagrant/action/builtin/handle_forwarded_port_collisions.rb

@@ -272,7 +272,7 @@ module Vagrant
             if test_host_ip == "0.0.0.0" || ipv4_interfaces.detect { |iface| iface[1] == test_host_ip }
               is_port_open?(test_host_ip, host_port)
             else
-              raise Errors::ForwardPortHostIPNotFound
+              raise Errors::ForwardPortHostIPNotFound, name: @machine.name, host_ip: host_ip
             end
           end
         end

templates/locales/en.yml

@@ -2321,10 +2321,13 @@ en:
           forwarding: Forwarding ports...
           forwarding_entry: |-
             %{guest_port} (guest) => %{host_port} (host) (adapter %{adapter})
-          host_ip_not_found:
+          host_ip_not_found: |-
             You are trying to forward a host IP that does not exist. Please set `host_ip`
             to the address of an existing IPv4 network interface, or remove the option
             from your port forward configuration.
+
+            VM: %{name}
+            Host IP: %{host_ip}
           non_nat: |-
             VirtualBox adapter #%{adapter} not configured as "NAT". Skipping port
             forwards on this adapter.

test/unit/vagrant/action/builtin/handle_forwarded_port_collisions_test.rb

@@ -233,9 +233,11 @@ describe Vagrant::Action::Builtin::HandleForwardedPortCollisions do
 
     context "when host ip does not exist" do
       let(:host_ip) { "127.0.0.2" }
+      let(:name) { "default" }
 
-      it "should raise an error" do
-        expect{ instance.send(:port_check, host_ip, host_port) }.to raise_error(Vagrant::Errors::ForwardPortHostIPNotFound)
+      it "should raise an error including the machine name" do
+        allow(machine).to receive(:name).and_return(name)
+        expect{ instance.send(:port_check, host_ip, host_port) }.to raise_error(Vagrant::Errors::ForwardPortHostIPNotFound, /#{name}/)
       end
     end
   end