Added Yahoo logo (Y on white bg) and Google (from Google favicon)

Signed-off-by: BARBIER J.M <jm.barbier@solidev.net>
Added OpenId logo

Signed-off-by: BARBIER J.M <jmbarbier@pcepepe.(none)>
Merge pull request #17 from jmbarbier/master

Added contributed Google favicon + Yahoo! + OpenId icons