Updated database, ER model and checkout process
Merge remote-tracking branch 'origin/fraenzi-branch' into simon-branch
Reviewed task from Fränzi

- Updated worklog (Brainstorming-ToDo)
- Re-added line (works as expected, try with a product that has "custom attributes"
Added product pictures

- Modified DB to no longer hold BLOBs but the image path
- Added logic to display product image to 'detail.php'
- Added three different product pictures
added ZendClientClass (unfinished)
Merge remote-tracking branch 'origin/simon-branch' into fraenzi-branch
adapted layout and css