Implement ImapFolderAgent.
Define expected payloads and reuse them.
Include "folder" in events.
Cover the "mark_as_read" option.
Check regexp validation.
Convert 'port' to integer.
Unbreak with Ruby <2.0 not having File::FNM_EXTGLOB.
Fix chef cookbooks to work with ubuntu 14.04

The primary issue was that libshadow-ruby1.8 is not
present in 14.04. The secondary one is that default
ruby in 14.04 is 1.9, so update-alternatives step
fails.

Fix:
* drop the requirement of libshadow-ruby1.8, since
we set 1.9 by default.
* see if 'ruby' points to 1.9 and update symlinks only
in case it doesn't
Elaborate on how to specify a case-insensitive pattern.
Mark duplicated mails as read even if event creation is skipped.
Document how this type of agent memorizes and deals with already seen mails.
Merge pull request #330 from racktear/ubuntu_14_04

Fix chef cookbooks to work with ubuntu 14.04
Merge pull request #328 from knu/imap_folder_agent

Implement ImapFolderAgent.
Created an IMAP agent that uses net/imap to return a filtered set of messages from a given mailbox provided some combination of subject, from, and to match.  It limits the returned messages based on a default time diff, or a memory saved last run time. It logs in with credentials keyed off of the e-mail account.
Removed an uneccessary logging statement
Found some e-mails did not use the same date/time formats, so switched the time parsing to use Time.parse instead.  Also corrected an oddity where if BEFORE and SINCE, in an imap search, are on the same day, it fails to filter.  In this circumstance I changed the search to use ON instead.
Merge branch 'IMAP_Agent' of https://github.com/viable-hartman/huginn into IMAP_Agent