Subtle border around non-text assets in viewer

Addresses #520
Merge branch 'develop' into 520-viewer_asset_border
Merge branch 'develop' into 520-viewer_asset_border
Add cssselect as a dependency.

It is needed by the way we use lxml, but at some point got broken out as
a separate package form lxml.

Addresses #564
Enable JDK for Travis build

Solr was complaining about a missing JDK.

Addresses #564
Remove duplicate wget lines

Addresses #564
Debugging messages for Solr on Travis

Addresses #564
Tell Jetty about the JDK

Addresses #564
Travis Solr debugging

Addresses #564
Point Jetty/Solr to correct Java on Travis

Addresses #564
Point Jetty at correct JDK

Setting JAVA_HOME didn't seem to work.  Trying to set JDK_DIRS.

Addresses #564.
Fix sed command from last commit

Addresses #564
Cleanup Travis build debugging

Closes #564
Merge branch 'develop' into 520-viewer_asset_border
Resize figure to wrap iframe

Previously, the figure was only resized to fit images, but I noticed that
it looked a bit odd with video content as well. YouTube seems to be the
most common video provider, and it uses IFRAMEs, so I modified the
figure-resizing code to size the figure captions and borders to wrap
IFRAMEs as well.

Addresses #520.
Updated the changelog to reflect #520

Closes #520
Use Haystack's SignalProcessors

In Haystack 2.0.0-beta, as of commit 041c480c8260dbe54feeeba52182f0788541d6b7, RealTimeSearchIndex is going away.

This commit follows the migration instructions to update to use
SignalProcessors instead of RealTimeSearchIndex.  The migration instructions
are at http://django-haystack.readthedocs.org/en/latest/migration_from_1_to_2.html#removal-of-realtimesearchindex

Addresses #570
Turn off Django debug mode for Travis tests

This is a workaround for toastdriven/django-haystack#716

Closes #570
Explicitly set django-notification version

Work around API change (see #571) until we can change code and test so
that we work with django-notification==1.0
Do the status='published' check to FeaturedManager

All the models that use FeaturedManager inherit from PublishedModel and
we probably don't want unpublished items on the homepage.  So, it makes
sense to do this check here.