Implement maildir mailbox

This a stub for the first mailbox format.

To add support for another mailbox implement it in <maildir_format>_mailbox.
When the user adds maildir_format = <maildir_format> the file will be required
and the new mailbox used automagically.

Author: expez

lib/mailbox/maildir_mailbox.rb

@@ -0,0 +1,24 @@
+class Maildir_mailbox
+  require 'mail'
+
+  def initialize maildir_path
+    @maildir_path = maildir_path
+    @maildir_path = "spec/fixtures/maildir"
+  end
+
+  def mail where={label: nil, folder: nil, from: nil, to: nil, date: nil}
+    Mail.read(@maildir_path + "/INBOX/cur/TRAIN_00001.eml")
+  end
+
+  def most_recent
+    mail
+  end
+
+  def labels
+    ["work", "cat pictures", "news"]
+  end
+
+  def folders
+    %w{ inbox archived spam trash }
+  end
+end