Hide earlier emails in a fact check received email chain

https://www.agileplannerapp.com/boards/173808/cards/8129

Avoid reproducing the original fact check email, and every other email in the reply chain, within the edition history and notes view. Instead show the most recent reply and hide all earlier emails behind a toggle, so that no information is lost.

Email detection is based on common patterns used by Outlook, OSX Mail, iPhone and BlackBerry. More can be added fairly easily, but this seems to have captured the majority of formats within existing notes.

The style of fact check emails has also been tweaked so that they appear different to regular notes, and can either be scrolled to or past with ease.

## Email
![screen shot 2014-11-24 at 12 52 13](https://cloud.githubusercontent.com/assets/319055/5165152/de716bf8-73d8-11e4-94a5-5a2413fb6f96.png)

## Expanded email
![screen shot 2014-11-24 at 12 52 51](https://cloud.githubusercontent.com/assets/319055/5165154/e2810096-73d8-11e4-878a-d9a32d0e02be.png)

these could be made more succinct by `assert_equal ["reply\n", "-----Original Message-----", "\noriginal"] split_email_at_reply(text)`. i understand that the separator is not an important bit to test, but whether `\n` gets picked-up is necessary, which may get lost while doing an `assert_match`.