Added additional flags for WIX_LIGHT only: ${WIX_LIGHT_FLAGS}

Usable in a scenario where one would need to link a localization file
(using -loc). However, if -loc is passed to ${WIX_LINK_FLAGS}, it will
cause problems with candle.
Merge pull request #97 from bor0/master

Added additional flags for WIX_LIGHT only: ${WIX_LIGHT_FLAGS}