Now all files dealing with repositories reside in app/repository and all
dealing with tag reside in app/tag. That's far more easy to maintain
than having tag files spread across multiple folders.
I did some cleanup and unified the deletion of items (e.g. tags or repos) a bit.
Now, you can select multiple repositories or tags and delete them at once.
Confirmation is done using a modal popup.
Success and error messages will still be prompted for each operation using
toastr notification.
One thing that is still missing is the selection of multiple items using some
automation like a stupid "select all" button.
Also, any selected item remains selected even if it does not show up any longer
due to filtering. That's why the delete buttons explicitly tell the number of
items to be deleted. This can cause issues when paging (not implemented yet) or
filtering.
