Fixed filename and attachment extraction of maildir

refs #5248

Cleaned up parsing of maildir attachment filenames out of
Content-Disposition by using the email library instead of doing it by hand.
Also parsed out the encoding of filenames, if it exists, and decoded them
to a unicode string.  Updated log messages to be more useful, and log file
format identification to fileFormatIdentification.log now.
FPRClient does not verify cert in settings.local