Remove duplicated data from legacy events

When event-tracking was fully integrated into the platform, some data was replicated in the context in the middleware and then later extracted and moved the old location by event-tracking. The legacy code path was not updated to remove this transient shim data from the context resulting in duplication of the information. This patch ensures that the transient information is removed from the context before emitting the event.

Fixes: AN-2369
Translate string iff non-empty

This resolves an issue where a checklist's long_description being empty
caused gettext to dump PO file headers.

I had originally made this change to the Stanford-Online/edx-platform
repository a few weeks ago [0] to address a failing test on our fork.
I didn't take the time to diagnose the root issue; I just fixed it for
the single case.

After stumbling across the issue elsewhere, @kluo <kevkluo@gmail.com>
followed through and tracked down the cause of the behavior. It turns
out that `gettext`, by default, translates the empty string into PO file
headers; this is apparently a feature, not a bug [1].

This behavior seems counterintuitive; for our use, it seems that
translating an empty string should simply return an empty string. We
already program defensively around this in platform code [2], but it'd be
convenient to resolve this with a centralized solution, instead of a
patchwork of fixes.

[0] 4b88f54aa658db952e899222ff5ede4a1c1beb18
[1] http://stackoverflow.com/questions/18459387/translation-of-empty-string-shows-po-header
[2] https://github.com/edx/edx-platform/blob/master/cms/djangoapps/contentstore/views/checklist.py#L140
Revert "bok-choy: check mysql the old way."
Merge pull request #4653 from Stanford-Online/stv/i18n/empty

Translate string iff non-empty
Merge pull request #4660 from edx/revert-4658-benp/fix-bok-choy-check

Revert "bok-choy: check mysql the old way."
Remove tooltip manager to get tests working in CMS again.
Merge pull request #4664 from edx/chrisitna/disable-tooltip-manager

Remove tooltip manager to get tests working in CMS again.
Add Eng (GB) and Albanian lang codes
Update translations (autogenerated message)
Merge pull request #4672 from edx/sarina/080414-translation-update

Sarina/080414 translation update
Merge pull request #4566 from mulby/remove-duplicate-context-fields

Remove duplicated data from legacy events
Annotation Tool: Flagging plugin should now allow instructors to remove flags from annotations

Annotation Tools: Added lots of comments, fixed spacing, fixed slice issue

Annotation Tools: i18n fixed for this tool

 - fixed Translator to Translators

Annotation Tools: Removed unnecessary class and worked with element object
Instructors can view previously sent email content

Previously on the send email page of the instructor dashboard, instructors could only view
task information about emails they've sent for their course in the past.
In addition to this, I've now added the ability to see the content of all previously sent emails.

A "Sent Email History" button has been added to the page. When clicked, a table displaying the
subject line, number of emails sent, and date/time of submission for each previously sent email
is created. An instructor can then click on any subject line to see the content of that email,
displayed in a modal window that appears on the page.

The window is also equipped with a "copy email to editor" button, which copies the emails contents
to the tinyMCE editor, so that an instructor can easily resend an email that they've sent
in the past.
Merge pull request #4378 from lduarte1991/lduarte-harvardx-pr10

Annotation Tool: Fixed Flagging for Instructor flag removal
Merge pull request #4451 from Stanford-Online/njdupoux/email-content-history

Instructors can view previously sent email content
Allow verified to be offered without audit
fixup! Allow verified to be offered without audit
Add the ability to override non-standard verified mode names