Allows contextual notes to be placed "around" node teasers on a taxonomy term page

* Provide plain text annotations before or after a node's teaser on a taxonomy term page
* For users with appropriate permissions, add contextual links to edit the annotation when viewing node teasers on a taxonomy term page
* Allow editing of annotations through a modal ajax form

This is useful if you would like to "introduce" or "add to" a teaser differently in different contexts.  For example a publication could be tagged in two different subject matters. And when looking at the subject matter specific pages an introduction about the importance or relivance is sometimes needed.