Move price tag url generation JS from template to coffee/.js.
Move price tag event binding to coffee/.js.
Move adding new tags form template to coffee/.js.
Add functionality for delete all vendor items button.

- Moved kirppu/page to kirppu/vendor/items as it sort of made sense for the
  deleting and viewing all items to happen in the same url.
- Change default state for new items to be advertized instead of staged.
- Restrict deleting items to only those with state == Item.ADVERTIZED.

Conflicts:
	kirppu/app/views.py
Fix code style issues.
Add item creation with suffixes.

- More than one item can be added at once by giving a list of suffixes.
Restyle the price tag form.

- Use bootstrap styles because it's easy, although a bit verbose.
- Add option for tiny price tags.
- Add help text.
Show price tags from newest to oldest.
Add tiny price tags.
Implement 1px high PNGs and make PNGs default format.

- Added a custom writer based on the ImageWriter that renders the barcode
  as 1px high PNG. Size from 2000 bytes to 120 bytes.
- Also removes text from images and positions the html text below the barcode.
Fine tune price tag sizes for printing.

- Firefox seems to render the tags a bit bigger in print preview than chrome.
  This is solved by using percentage widths. It breaks landscape printing a
  bit but that shouldn't matter if portrait works.
Add missing for attributes to price tags form.
Make enable delete buttons affect the delete all button as well.
Fix PyCharm warnings.
Move form event binding to coffee/.js.
Add some input validation to price tag form price.
Fix price checks on price update and item add.

- There were not a whole lot of checks for these yet, but they should now
  work as expected.
Adds way to change modes from menu

* Menu can be enabled and disabled via switcher.
* Changed menu to be dropdown.
* Menu items have now "descriptive" icons.
* Using the menu, current mode can be changed.
Changed createRow to be a bit more robust with price-variable

Price formatted as price only if it is number. Otherwise, rounding is
disabled and the value (or blank default) is displayed as-is.
Adds success-class for rows generated in finish receipt.