Fix key import.
Fix key import.

Fix multiple small flaws in the key import.
- First, allow to have multiple keys matching the search query, prompt
  the user for which one to use.
- Add s to --export-secret-keys option used to remove possibility of
  ambiguity.
- Export the secret key really when we say we are doing it.
- Commit when we are done with all calls for an atomic add.

trustly/bankapi,trustly/bankapi,ADemonisis/bankapi,ADemonisis/bankapi