Update presentations.md
Merge pull request #23 from merilainen-metropolia/patch-1

Update presentations.md
Tasks for today
Video link was in a wrong place
Presentation dates added
Valittiin aiheet
Merge pull request #38 from Markoham/master

Presentation dates added
Merge pull request #39 from anttev/master

Valittiin aiheet
Link to example repository