Removed trailing whitespaces

Signed-off-by: Lars Kiesow <lkiesow@uos.de>
Fixed issue #18, Notice when removeing a non-existing key

When one tried to remove a non-existing key, an error status was
returned but no message for the user was displayed. This is now fixed.
The command will terminate without error but will notify the user that
no key existed in the first place.

Signed-off-by: Lars Kiesow <lkiesow@uos.de>