Add optional arg for auto retrival of all mails	in specify mailbox Bound allows for same lower and upper bound for listing a single mail
Add optional arg for auto retrival of all mails	in specify mailbox
Bound allows for same lower and upper bound for listing a single mail

Order of message is change to download from oldest to newest
So that it wouldn't miss a mail when using auto retrival

Idea from @mtarnawa: https://github.com/appleorange1/openmailbox_downloader/pull/1#issue-248169909

asl97/openmailbox_downloader