Add Win64 or WOW64 to user agent string as appropriate.
Add Win64 or WOW64 to user agent string as appropriate.

Add "(Win64)" to the user agent string when running 64bit binary. Add
"(WOW64)" when running a 32bit one, but on 64bit Windows OS.

This is consistent with what most browsers do and it's useful for
determining what updates to serve. For example, a WOW64 installation may
get an update to convert it to natively 64bit version.

Fixes pull request #5 (with a different, more robust implementation).

Herve-M/winsparkle,artillery/winsparkle,dsuess/winsparkle,bristol-instruments/winsparkle,artillery/winsparkle,nickdademo/winsparkle,drizt/winsparkle,alamaison/winsparkle,dsuess/winsparkle,CaptainJackJJ/SmpUpdater,bristol-instruments/winsparkle,CaptainJackJJ/SmpUpdater,Herve-M/winsparkle,alamaison/winsparkle,nickdademo/winsparkle,drizt/winsparkle