Bug 947211 - [Messages][Drafts] Thread message/draft status (preview, styling and icon) is not accurate for various cases

https://bugzilla.mozilla.org/show_bug.cgi?id=947211
Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
Bug 950914 - [Messages][Drafts] Replace existing draft when hiding app while showing unsent, existing draft content