Course Updates date validation

Adding i18n info for developers

Decreased the flakiness of upload_tar function

Remove unused imports

Submission History safe by default

TNL-4115. Previously, course updates (which are intended to be posted with
dates, for sorting in the LMS) could be authored in studio with a valid
date, nothing, or a random string as the "date" for the update. As there
is no validation for this in studio, everything succeeded with no warning.

However, the LMS has problems parsing some of these values, and barfs when
loaded by learners.

The fix does two big things:
- gracefully handles invalid dates in LMS. These updates are now treated as
having a date of today, for sorting purposes.
- turns on validation in studio. Now, it is not only impossible to enter
invalid dates in studio, but notifications will draw the course author's
eye if any invalid updates were previously saved.

Test additions for this commit:

Adds:
- unit test for LMS parsing
- Jasmine test to confirm invalid dates cannot be set by the user
    -also adds event to setAndValidate instead of using a global object
- fix for lettuce test
    -It is no longer valid to enter the string "January 1, 2013" as this test
    had been doing. Keyed-in entries must use MM/DD/YY format.

Fix sequence navigation issues for CCX courses

Upgraded xblock-lti-consumer to 1.0.5

Stripping auth querystring from S3 URLs

asadiqbal08/WL-409 updated ubcpi version

Safe  template for edxnotes.

Add registerd trademarked logo to footer.

MA-2258

We use S3 for a number of uploads. Boto, by default, includes a auth querystring on the returned URLs. Since these uploads are public, there is no need for this querystring. Additionally, the long length URLs cause problems when API consumers need to store the URLs. This commit resolves this problem by removing the auth querystring.

- Updated to latest versions of boto and django-storages-redux packages
- Added AWS_QUERYSTRING_AUTH setting to remove the querystring values

ECOM-4081

Efischer/merge release to master

Bump ora2 version

AC-223 updating transcript skip links

Merge release into master

Fixed unable to created ccx issue 

Patch/2015 04 06

asadiqbal08/WL-388: Add ModuleI18nService for Descriptor System

Making migrations in-sync with models.

TNL-4296

TNL-4296