Update xblock for Hawthorn version of Platform

• switches from get_template() to render_django_template()
• pushes xblock-utils requirement to v1.1.1
• updates tests

No Peer Responses display Bugfix

Text to be displayed in cases of incorrect answer or when there are no responses wasn't being put in the template properly. This fixes that.

Fix Peer Responses

• Show peer responses on page load if answer was correct
• Change "Show"/"Hide" link for peer responses to show current and next states
• Allow text in HTML to be translated
• Fix pep8/pylint on modified files

Makes comparison between TZ naive UTC dates

Dates are stored on platform in UTC.

This release makes this xblock compare platform duedates as UTC timezone naive objects to the current UTC time.

Makes xblock due_date & graceperiod aware

XBlocks do not follow platform due dates by default.

This release amends this XBlock to make it close submissions if the platform's subsection due-date has passed. The courses graceperiod is taken into account.

Move cached data from body to seq_content

Previously, some future update or rogue script could easily tamper with
our cached data attributes on the body element. We moved these data
attributes to be slightly less widely accessible.

Dev: @potsui

Suppress IntegrityError exception

• Fix the IntegrityError that occurs when publishing a score in _compute_score
• Added a unit test to check the IntegrityError Exception

Add cache to display answer after submit or save

Feature by @potsui

Previously in the free-text response xblock, when a user submits or
saves an answer, navigates to another page, and navigates back to the
original page, the user's answer disappears. Refreshing the webpage will
restore the answer, but this was nonetheless a disconcerting experience
for the user.

This fix caches the user's answer to display after submit or save, so
that when the user navigates away and back, the user can still view
their answer without having to manually refresh the page.

Fix html tags studio prompt bug introduced in v0.1.3

Updating the html templates to use Django's templateing broke the User's ability to add html tags to the prompt box in Studio settings. This adds the needed tag, 'safe', to the html element. This also removes an line in the Gruntfile that is not needed since html templates are not monitored during grunt watch.

Localize xblock with vietnamese translations

Merge pull request #16 from caseylitton/update-to-version-0.1.3

Update to version 0.1.3