Typo

Fixed undefined local variable or method 'filename' exception raised when using pre_postinstall_file option. Refers to #575.
explicit include of json gem
no need for a vagrant alias
put em-winrm in a separate group
moved em-winrm to a seperate bundle group to achieve ruby-1.8.7 compatibility
Merge pull request #616 from zyegfryed/patch-1

Typo (filename -> pre_filename)
gentoo-amd64 - always get latest stage3, bump kernel version, use emerge-webrsync for first sync, workaround for autofs bug
gentoo-i686 - always get latest stage3, bump kernel version, use emerge-webrsync for first sync, workaround for autofs bug
Merge pull request #635 from davidmmiller/master

fixes for Gentoo amd64 and i686