installer adds information for the registry, including icon and actions for .rockspec files when /R argument is provided.
includes the new luarocksw.bat batch file
also: made the /P argument of the installer required
fixes in registry template and batchfile luarocksw.bat
added default command "edit", so when double clicking it won't automatically install, but open notepad. A safer option.
Merge pull request #114 from Tieske/Regsitry_info_added

implements .rockspec file extension on windows