Req 2.2.2: Show reservation options

Stork is able to show host reservations with some details, but options are not displayed.

The complex part here is that options can have varied syntax (string, boolean, address, integers, structure, empty, etc).

This requirement calls to display the options and their values somehow.

In particular anything related to PXE should be displayed.

This is a follow-up to Req 2.2: #45 (closed).