Information about expired qualifications

[jeriox]

As a user, I want to be informed about expired qualifications. This includes:

• a notification (via mail etc) when the qualification expires
• visually highlighting expired qualifications on my profile page
• a hint on the home page

Optionally this includes some kind of link to renew the consequence (shortcut to #253)

[jeriox]

also provide this information about other users to those who can edit userprofiles