Edited create_package.py to include a line changing the permissions of /Library/Preferences/com.apple.loginwindow.plist back to 0644.

Fixes an issue when installing on a non-booted sytsem (instadmg) where the permissions get changed to 0600.
Merge pull request #27 from chilcote/loginwindow_prefs

Edited create_package.py to include a line changing the permissions of /...