Make default avatar images public to allow Gravatar proxying

htdocs/admin/company.php

htdocs/core/class/html.form.class.php

htdocs/public/theme/common/index.php

htdocs/public/theme/common/nophoto.jpg

htdocs/public/theme/common/user_anonymous.png

htdocs/public/theme/common/user_man.png

htdocs/public/theme/common/user_woman.png

htdocs/public/theme/index.php

htdocs/viewimage.php