Email content history fix and additions

This addresses a bug in the email content history table where
"Unknown" was displayed in the number of emails sent column if any sort of
failure occurred during email sending. This behavior has been edited so now
the number of emails that failed to send is displayed, along with the number
of emails that were successfully sent. If the email task is still pending,
"0 sent" is displayed.

As a small addition, the table now also includes the authors of previously
sent emails, and the modal window for an email also displays its author.
Right but no where in the email will it say that it is "from" this staff
member! It will say "xxx Course Staff". I'm confused why you show screen
shots of an email client.
On Aug 11, 2014 12:52 AM, "Steven Burch" <notifications@github.com> wrote:

> In lms/static/coffee/src/instructor_dashboard/util.coffee:
>
> > @@ -154,6 +158,14 @@ create_email_content_table = ($table_emails, $table_emails_inner, email_data) ->
> >        cssClass: "email-content-cell"
> >        formatter: subject_formatter
> >      ,
> > +      id: 'requester'
> > +      field: 'requester'
> > +      name: gettext('Author')
>
> TL;DR: In retrospect, I probably shouldn't have even mentioned the RFC and
> simply said, "because 'From' is what nearly every email client says".
>
> ... *it's short/simple*
>
> ...
> *it's the term most likely to match what users are accustomed to seeing in
> their respective email clients*.
>
> My rationale wasn't that end-users would prefer "From" because of the
> specification, but rather because of convention.
>
> Because of its inclusion in the specification, *every* email client has
> a concept of "From", as its one of the defining characteristics of an
> email message, being one of the few required fields. Consequently, email
> client developers have mirrored this language in their user interfaces.
> Every [0] email [1] client [2] I [3] use [4] tells me "From" whom a
> message was
> sent, not by whom it was "Sent" nor who was the "Author".
>
> From this perspective, *any* term beyond "From" is a departure from
> convention.
>
> Either way, I won't lose sleep, so I defer to UX.
>
> [0] [image: 0]
> <https://camo.githubusercontent.com/caa18206f6b1bb480d6a16db00fa02b846a937ad/687474703a2f2f39746f356d61632e66696c65732e776f726470726573732e636f6d2f323031342f30312f616464616c696e652e706e67>
> [1] [image: 1]
> <https://camo.githubusercontent.com/01962a0747cc009f1739f6fdcac95f713d12b09d/687474703a2f2f6730342e636f6d2f696d616765732f676d61696c2f676d61696c5f66696c7465722e6a7067>
> [2] [image: 2]
> <https://camo.githubusercontent.com/177acc220adb4d020ef2c6c506846233d8c0a8b6/687474703a2f2f756e74657468657265646f66666963652e636f6d2f77702d636f6e74656e742f75706c6f6164732f323031302f30372f456d61696c2d46696c746572732d616e642d466f6c646572732d7468756e646572626972642d66696c746572732d65313237393138333734303339332e706e67>
> [3] [image: 3]
> <https://camo.githubusercontent.com/b8c8c0694d5b1e737a78f6e96bf19c055e2ad85d/687474703a2f2f7777772e75786d6174746572732e636f6d2f6d742f61726368697665732f323030392f30372f696d616765732f6669677572655f355f686f746d61696c2e706e67>
> [4] [image: 4]
> <https://camo.githubusercontent.com/1ed22b534ecfc27615d541722fa83089028bf02e/687474703a2f2f68656c702e7961686f6f2e636f6d2f6370702f696d616765732f6367332f63675f61646466696c74315f79705f312e676966>
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/edx/edx-platform/pull/4746/files#r16037404>.
>