Update README file with info about building with stock GTK+.
Update README file with info about building with stock GTK+.

community-ssu/hildon,android-808/libhildon,archlinuxarm-n900/libhildon,android-808/libhildon,Cordia/libhildon,community-ssu/hildon,community-ssu/hildon,android-808/libhildon,Cordia/libhildon,Cordia/libhildon,archlinuxarm-n900/libhildon,archlinuxarm-n900/libhildon