Whenever GPGFinishRecipientsBuffer is called, the buffer is processed to
convert names to IDs. However, this was ignoring any existing ID information
in the buffer. This meant that if a person had multiple keys, the user would
be prompted to disambiguate the keys after every :GPGEditRecipients session.
Parsing the ID out of the recipients buffer avoids the unnecessary prompting.
Signed-off-by: James McCoy <vega.james@gmail.com>