Release Name: 1.0.8

Notes:
* Several constants changed from -1 to 0xFFFFFFFF


Changes:
* Several return value constants that were set at -1 are now set to
  0xFFFFFFFF instead because win32-api returns unsigned longs.
* Removed the two mailslot constants from the Windows::File module. They're
  defined in the Windows::Mailslot module.
* Added the windows_version method to the Windows::SystemInfo module. It
  returns a float in 'major.minor' format.