rework app concept

[bodokaiser]

Rework app concept in order to provide better user experience and to percept the shop actually as a shop (which is currently not necessarily given...).

To-Dos:

• [x] move /store/* to /(replaces main)
• [x] redesign navbar with order button
• [x] remove current store sidebar
• [x] extend small product info in product list
• [x] create product detail view at /products
• [x] create new product document for different colors
• [x] move order items list to /order
• [x] move customer form to /order/customer

[bodokaiser]

Further rework requires clarification about the order process.