Remove rotation for older IE versions.

It was doubly rotating the tab in IE9.  If we're supporting older
versions, we should detect if a rotate property is supported and only
apply the currently commented style if needed.

Closes #414.
Merge branch 'develop' of github.com:PitonFoundation/atlas into develop
First pass at IFRAME uploads

Internet Explorer <= 9 doesn't support the HTML5 File API, so we have to
append a hidden IFRAME and submit the form to the IFRAME to fake an AJAX
upload.

I've only added support for this for asset uploading.  Still to do is
implementing this for the featured asset and dataset uploads.

Partial fix for #236
Add IFRAME upload support for data sets.

Partial implementation of #236.
IFRAME upload support for featured images.

Fakes AJAX upload of files in IE9

Partial implementation of #236.
Add imgur oEmbed support.

This is mostly for testing just because I have a lot of images on imgur.
Allow changing featured asset in same session.

There was a bug that was keeping featured assets from being changed
multiple times without a page reload because the form model wasn't being
reinstantiated.
Merge branch '314-explore_show_more' into develop

Conflicts:
	static/css/style.css
Merge remote-tracking branch 'eric/master' into develop
Only return explicit places in API

The lookup for inherited places is expensive and we're not really using
that anywhere except for updating the Solr index, and in that case,
Story.inherited_places is called directly.
Don't retrieve default featured asset, set it

When a story doesn't have a featured asset explicitly defined, we've
been using the first image asset.  Previously, the code did this each
time the featured asset was requested.  It's kind of expenseive in terms
of database use, so it seemed better to do it once when the story is
published instead of each time the story data is fetched.  I added a
pre_save signal handler to auto-assign a featured asset if none is
explicitly specified.

The pre_save signal should be triggered for all existing stories, just
to make sure a featured asset is set (since it will no longer have a
default retrieved on access).  This can be done by just saving each
published story:

    from storybase_story.models import Story
    for s in Story.objects.filter(status='published'):
        s.save()

Partial fix for #455
Merge branch '468-link_to_release_form' into develop
Merge branch '470-publish_step_layout' into develop
Merge branch '471-featured_asset_bullets' into develop
Merge branch '471-featured_asset_bullets' into develop
Merge branch 'weekly-0.1.5' into 455-explore_page_performance
Merge branch 'weekly-0.1.5' into 455-explore_page_performance
Use values() to select fields to retrieve.

Not selecting the boundary from the database (we don't use it anyway)
really speeds up the query.
One query for featured assets instead of two.

Since we ultimately want to display the asset and expect it to exist, we
should just try to pull everything instead of checking that it exists
first.
Utility function for generating a cache key

This function generates a cache key for a model instance. It is based on
the pattern described at

http://eflorenzano.com/blog/2008/11/28/drop-dead-simple-django-caching/

but takes an extra argument to specify additional parts to the key since
(for now at least), I'm not caching the whole model, just certain
model-based properties.