Use VBOX_INSTALL_PATH on Windows to find VBoxManage [GH-609]

lib/vagrant/driver/virtualbox.rb

@@ -1,5 +1,6 @@
 require 'log4r'
 require 'vagrant/util/busy'
+require 'vagrant/util/platform'
 require 'vagrant/util/subprocess'
 
 module Vagrant
@@ -26,6 +27,21 @@ module Vagrant
         # This flag is used to keep track of interrupted state (SIGINT)
         @interrupted = false
 
+        # Set the path to VBoxManage
+        @vboxmanage_path = "VBoxManage"
+
+        if Util::Platform.windows?
+          @logger.debug("Windows. Trying VBOX_INSTALL_PATH for VBoxManage")
+
+          # On Windows, we use the VBOX_INSTALL_PATH environmental
+          # variable to find VBoxManage.
+          if ENV.has_key?("VBOX_INSTALL_PATH")
+            @vboxmanage_path = "#{ENV["VBOX_INSTALL_PATH"]}\VBoxManage.exe"
+          end
+        end
+
+        @logger.info("VBoxManage path: #{@vboxmanage_path}")
+
         if @uuid
           # Verify the VM exists, and if it doesn't, then don't worry
           # about it (mark the UUID as nil)
@@ -481,7 +497,7 @@ module Vagrant
         end
 
         Util::Busy.busy(int_callback) do
-          Subprocess.execute("VBoxManage", *command, &block)
+          Subprocess.execute(@vboxmanage_path, *command, &block)
         end
       end
     end