GetKeySection: Made it to import a key from a local file into a temporary
keyring. Made it to also verify if the key imported has the same fingerprint
as the one that was scanned(in this case hardcoded in on_button_clicked).
Added a TmpKeyring class that inherits TempKeyring (and also Keyring) from monkeysign module.This is because the import_data method from monkeysign.gpg.Keyring doesn't offer a way to import a key from a file, or I do not know how to use it properly.