Update steam.spec

I modified Requires for to group in fedora and suse, also i have renamed all packages of suse with their real package names

For harfbuzz in suse libharfbuzz0 is necessary add this repo:
http://download.opensuse.org/repositories/GNOME:/STABLE:/3.6/openSUSE_12.2/
Merge pull request #8 from Mad-Soft/patch-1

Update steam.spec