AOSP Email app supports reply-to but it's not used for default when using imap.

This commit originates from http://pastebin.com/R0QPpnft, author unknown.

When fetching email, also fetch the reply-to field (when using IMAP),
as it will be used, but currently is not fetched, and thus is not used

Change-Id: I7657b19d643ba5976abdae0aac458633e4297383
Merge "AOSP Email app supports reply-to but it's not used for default when using imap." into du44