Convert hostpath to string on windows so gsub works

CHANGELOG.md

@@ -1,6 +1,9 @@
 ## 1.2.7 (unreleased)
 
+BUG FIXES:
 
+  - On Windows, properly convert synced folder host path to a string
+    so that separator replacement works properly.
 
 ## 1.2.6 (July 26, 2013)
 

plugins/kernel_v2/config/vm.rb

@@ -128,7 +128,7 @@ module VagrantPlugins
         if Vagrant::Util::Platform.windows?
           # On Windows, Ruby just uses normal '/' for path seps, so
           # just replace normal Windows style seps with Unix ones.
-          hostpath.gsub!("\\", "/")
+          hostpath = hostpath.to_s.gsub!("\\", "/")
         end
 
         options ||= {}