Add buttons to allow edit from players in shared field

[louisroyer]

And a message:

• "They are able to use the keyring but not to manage keys." -> "Allow key management"

• "They are able to use the keyring and to manage keys." -> "Deny key management"

• [x] add keyring.fields.utils.owner.is_key_management_allowed + corresponding field _keyring_shared_key_management (int to 1 or 0)

• [x] update formspec.lua to display buttons

• [x] update formspec.lua to allow removing of keys if key edition is allowed (+ interface displaying for removing/renamming)

• [x] update craft_common to allow craft if key edition is allowed, and to set the resulting owner correctly (+ in craft prediction)

• [x] update translation

• [x] test

• [x] update screenshot_2.png

• [x] update init.lua version and release a new version