Add error for when disks defined are greater than the max limit

lib/vagrant/errors.rb

@@ -904,6 +904,10 @@ module Vagrant
       error_key(:virtualbox_broken_version_040214)
     end
 
+    class VirtualBoxDisksDefinedExceedLimit < VagrantError
+      error_key(:virtualbox_disks_defined_exceed_limit)
+    end
+
     class VirtualBoxGuestPropertyNotFound < VagrantError
       error_key(:virtualbox_guest_property_not_found)
     end

plugins/providers/virtualbox/cap/configure_disks.rb

@@ -19,10 +19,8 @@ module VagrantPlugins
           return if !Vagrant::Util::Experimental.feature_enabled?("virtualbox_disk_hdd")
 
           if defined_disks.size > MAX_DISK_NUMER
-            # TODO: THORW AN ERROR HERE
-            #
             # you can only attach up to 30 disks per controller, INCLUDING the primary disk
-            raise Exception, "fix me"
+            raise Vagrant::Errors::VirtualBoxDisksDefinedExceedLimit
           end
 
           machine.ui.info("Configuring storage mediums...")

templates/locales/en.yml

@@ -1641,6 +1641,11 @@ en:
         4.2.14 contains a critical bug which prevents it from working with
         Vagrant. VirtualBox 4.2.16+ fixes this problem. Please upgrade
         VirtualBox.
+      virtualbox_disks_defined_exceed_limit: |-
+        VirtualBox only allows up to 30 disks to be attached to a single guest using the SATA Controller,
+        including the primray disk.
+
+        Please ensure only up to 30 disks are configured for your guest.
       virtualbox_guest_property_not_found: |-
         Could not find a required VirtualBox guest property:
           %{guest_property}