Add a new route for image upload
This pull request introduces a new route for users to upload images/files without the need to open the full labbook on their device. The new route can be accessed via https://labbook_url.de/upload and will show all lab books the user currently has write access to; with the most recently selected on top; and an upload button (file select). Additionally, with mobile browsers, users can directly start the camera with one button.
Feedback and suggestions are welcome.
Added a new route
Direct camera upload
Same layout as home
Closes #49 (closed)