Some improvements to the current version

I did some bugfixes to the current version.

Some bugs did popup the last weeks, which I said I would fix in the next version.

And I did, but since I can't let you wait for a next version and in the meanwhile let you use a bugged version, I have done those bugfixes in this version as well.

I did the following fixes:
- birthdays are formatted right this time, ages are calculated correctly. (I had to clear everyones birthday, so you have to fill it in again)
- avatars are editable again (yes hoorray! :))
- homepage is a bit cleaner (announcements aren't full displayed, only teasers are shown)
- improved help section
- improved help search function