New feature: Upload an image for an item.
fixed bug: now you can create an item with an image.
fixed bug:
- it's not possible to buy changed items anymore.
- it's not possible to deactivate a sold item anymore.
(solved this problem by comparing the user.open_item_page_time with the item_edit_time:
if user.open_item_page_time < item.edit_time then the transaction or the deeactivation won't work.)
fixed bug:
- it's not possible to buy changed items anymore.
- it's not possible to deactivate a sold item anymore.
(solved this problem by comparing the user.open_item_page_time with the item_edit_time:
if user.open_item_page_time < item.edit_time then the transaction or the deeactivation won't work.)

Fixed bug: It's possible to edit/create item without any image
First working version of activity logging. Tracked activities now include item creation, item update, item status change, item purchase
Moved a few logic to model instead of controller

	modified:   trade/app/app.rb
	new file:   trade/app/controllers/activity_logger.rb
	modified:   trade/app/controllers/item.rb
	new file:   trade/app/models/analytics/activity.rb
	new file:   trade/app/models/analytics/activity_logger.rb
	modified:   trade/app/models/storage/database.rb
	modified:   trade/app/models/store/item.rb
	modified:   trade/app/models/store/user.rb
	new file:   trade/app/views/activity.haml
	new file:   trade/app/views/all_activities.haml
	modified:   trade/app/views/layout.haml
	new file:   trade/test/activity_logger_test.rb
	new file:   trade/test/activity_test.rb
fixed bug:
- it's not possible to buy changed items anymore.
- it's not possible to deactivate a sold item anymore.
(solved this problem by comparing the user.open_item_page_time with the item_edit_time:
if user.open_item_page_time < item.edit_time then the transaction or the deeactivation won't work.)

Fixed bug: It's possible to edit/create item without any image
The evil.py script changes the information of the item directly with its setters, without pushing the deactivate button. So I overwrote the important setters and there I added:
self.edit_time = Time.now, to refresh the edit_time of the item.
Now the script fails.
Improved image upload:
- If the user changes the image, the system automatically deletes the old unused image(=>uses less memory space)
- If the user doesn't change the image in the edit mode, the image stays the same.
Added item delete activity and improved activity inheritance

Activities now store relevant information directly so items and users don't need to be present in the system anymore

	modified:   trade/app/controllers/item.rb
	modified:   trade/app/models/analytics/activity.rb
	modified:   trade/app/models/store/item.rb
	modified:   trade/app/models/store/user.rb
	modified:   trade/test/activity_test.rb
Removed not needed code

	modified:   trade/app/models/analytics/activity.rb
Fixed stupid copy paste mistake

	modified:   trade/app/models/analytics/activity.rb
Prepared activity details view, controller

	modified:   trade/app/controllers/activity_logger.rb
	modified:   trade/app/public/styles.css
	modified:   trade/app/views/activity.haml
	modified:   trade/app/views/all_activities.haml
Made tests work again

	modified:   trade/app/models/store/user.rb
	modified:   trade/test/activity_logger_test.rb
	modified:   trade/test/activity_test.rb
Added support for markdown item descriptions using rdiscount gem

The enhanced markdown parser even filters <script> tags savely \0/

	modified:   .idea/ese2011-web-ui.iml
	modified:   Gemfile
	modified:   Gemfile.lock
	modified:   trade/app/controllers/item.rb
	modified:   trade/app/public/styles.css
	modified:   trade/app/views/item.haml
Improved image upload:
- If the user changes the image, the system automatically deletes the old unused image(=>uses less memory space)
- If the user doesn't change the image in the edit mode, the image stays the same.
Merge branch 'om' into merger

Conflicts:
	.idea/ese2011-web-ui.iml
	trade/app/controllers/item.rb
	trade/app/controllers/main.rb
	trade/app/controllers/user.rb
	trade/app/models/store/user.rb
	trade/app/views/item.haml
	trade/app/views/partials/item_edit_form.haml

	modified:   trade/app/controllers/item.rb
	modified:   trade/app/controllers/main.rb
	modified:   trade/app/controllers/user.rb
	modified:   trade/app/models/store/item.rb
	modified:   trade/app/models/store/user.rb
	new file:   trade/app/public/images/6_homer-sleep.jpg
	modified:   trade/app/views/edit_item.haml
	modified:   trade/app/views/error.haml
	modified:   trade/app/views/item.haml
	modified:   trade/app/views/partials/item_edit_form.haml