Fixes no validation on category dropdown which causes errors

If you add or edit a product and don't choose a category, you could still add the product. This caused a Spoon exception. The validation on the category_id dropdown didn't seem to be working.
Fixes media images sequence
Merge pull request #6 from jessedobbelaere/fix-validation-category

Fixes no validation on category dropdown which causes errors
Merge pull request #7 from jessedobbelaere/fix-media-sequence

Fixes media images sequence
Updated changelog

Added bugfixes for upcoming new version
Fixed issue #5

Added a input field to shopping cart overview, removed dropdown with
amount for adding to shopping cart
Updated changelog
Updated changelog
Updated version
CamelCasing files & folders
Upgrading to Fork v3.7.1

Added namespaces, CamelCasing template path in templates
Upgrading to Fork v.3.7.1

Reformatting the installer
Upgrading to Fork v3.7.1

Deleted old folders
Upgrading to Fork v3.7.1

Added new files
Upgrading to Fork v3.7.1
Upgrading to Fork v3.7.1

Inserted classes for backend actions
Upgrading to Fork v3.7.1

Inserted classes for frontend actions
Upgrading to Fork v3.7.1

Replacement of CommonCookie
Upgrading to Fork v3.7.1

Replacement of CommonCookie, Path names, backendmodel mentioning in
frontendmodel
Upgrading to Fork v3.7.1

Replaced CommonCookie, Paths to CSS/JS