Use Shared IP from DHCP instead of detecting it via VM option.

VM options work only if Parallels Tools installed in the guest. So, we should to use universal
approach to support NFS in such guests as CoreOS, FreeBSD, OmniOS and so on.

Related to: [GH-152]

lib/vagrant-parallels/action/prepare_nfs_settings.rb

@@ -36,40 +36,16 @@ def call(env)
         #
         # The ! indicates that this method modifies its argument.
         def add_ips_to_env!(env)
-          host_ip = @machine.provider.driver.read_shared_interface[:ip]
+          host_ip  = @machine.provider.driver.read_shared_interface[:ip]
+          guest_ip = @machine.provider.driver.read_guest_ip
 
-          if !host_ip
-            # If we couldn't determine host's IP, then it is probably a bug.
-            # Display an appropriate error message.
-            raise Vagrant::Errors::NFSNoHostIP
-          end
+          # If we couldn't determine either guest's or host's IP, then
+          # it is probably a bug. Display an appropriate error message.
+          raise Vagrant::Errors::NFSNoHostIP  if !host_ip
+          raise Vagrant::Errors::NFSNoGuestIP if !guest_ip
 
           env[:nfs_host_ip]    = host_ip
-          env[:nfs_machine_ip] = read_machine_ip
-        end
-
-        # Returns the IPv4 addresses of the guest by looking at VM options.
-        #
-        # For DHCP interfaces, the ip address will be present at the option
-        # value only after VM boot
-        #
-        # @return [String] ip addresses
-        def read_machine_ip
-          # We need to wait for the guest's IP to show up as a VM option.
-          # Retry thresholds are relatively high since we might need to wait
-          # for DHCP, but even static IPs can take a second or two to appear.
-          retryable(retry_options.merge(on: Errors::ParallelsVMOptionNotFound)) do
-            ips = @machine.provider.driver.read_vm_option('ip').split(' ')
-            ips.select! { |ip| IPAddr.new(ip).ipv4? }.sort
-          end
-        rescue Errors::ParallelsVMOptionNotFound
-          # Display an appropriate error message.
-          raise Vagrant::Errors::NFSNoGuestIP
-        end
-
-        # Separating these out so we can stub out the sleep in tests
-        def retry_options
-          {tries: 7, sleep: 2}
+          env[:nfs_machine_ip] = guest_ip
         end
       end
     end

lib/vagrant-parallels/driver/meta.rb

@@ -88,6 +88,7 @@ def initialize(uuid=nil)
                        :import,
                        :read_bridged_interfaces,
                        :read_forwarded_ports,
+                       :read_guest_ip,
                        :read_guest_tools_state,
                        :read_guest_tools_iso_path,
                        :read_host_only_interfaces,
@@ -100,7 +101,6 @@ def initialize(uuid=nil)
                        :read_state,
                        :read_used_ports,
                        :read_virtual_networks,
-                       :read_vm_option,
                        :read_vms,
                        :read_vms_info,
                        :read_vms_paths,