Add copy pages for devices and platforms

Issue #41 (closed)

In order to provide some basic copy functionality.

It will add forms with the basic data to edit - as well as checkboxes to copy also related entities (contacts, measured quantities, custom fields, attachments), but no actions (as those represent the history of a specific device).

It will unset the pid, serial & inventory number - but it can display those as placeholders in case they were set (in the hope to support for cases of numbers like "xxxx-1", "xxxx-2", "xxxx-3", ...).