content views - support retrieving 'readable' versions

A small change to add an authorization to allow users to
retrieve content view versions that are 'readable' within
an organization.
content views - add a portlet to the dashboard for content views

This commit contains changes to add a portlet to the dashboard for
content views.  The portlet will be similar to what is available
for promotions.

It will essentially list the last N (e.g. 5) content view
publish/refresh attempts.  Indicating 'publishing' or 'refreshing'
while the view action is being performed.  Once it is finished,
it will display success/failure with a timestamp.  The user
may also click on the view name (if they have permissions)
and be redirected to to the content view definition where
that view exists.
content views - haml for dashboard portlet
Merge pull request #1697 from bbuckingham/fork-content_views_dashboard

content views - add a portlet to the dashboard for content views