Log Message:
Update plone3 package to 3.1.2.

* Correct registration of the Sarissa javascript library: current KSS uses it
  as well. Fixes bug 8141.
* Correct handling of external links in the portal section tabs. Fixes bug 7155.
* Correct display of sub-collections. Fixes bug 8159.
* Use a custom permission for collection portlets so users can use it on their
  dashboard.
* Fix handling of unicode versioning comments. Fixes bug 7400.
* Update translations.
* Do not allow backquotes in URLs but replace them with a dash.
* Make CSS classes for the navigation tree more consistent.
* KSS updates:
      o kss.demo is no longer required.
      o Improve support for Sarari 3.1.
      o Correct logging of doubly registered actions.
* Update the quick installer tool:
      o Log ImportErrors in installation methods instead of silently ignoring
        them.
      o Sort products by title instead of id. This fixes bug 8012.
      o Fix installation/upgrade of products which had pre-Plone 3.0/CMF 21
        style actions.
* Update the kupu visual editor:
      o Add a hint for Deliverance so it will not style kupu pages.
      o Fix Plone bugs 7779, 7958, 7990, 8003, 8009, 8014, 8039, 8080, and
        8129 .
* Update Zope:
      o Bug 142350: Display description for properties as row title, if present.
      o Bug 143813: zopectl now exits non-zero when child processes fail.
      o Bug 164783: Indexes were migrated on initial creation of a ZODB.
      o Bug 173658: Removed dead code in OFS.Traversable's
        unrestrictedTraverse (apparent NameError).
      o Bug 198274: "empty" ZopePageTemplates could not be unpickled.
      o Bug 200007: DateTime(anotherDateTime) now preserves the timezone.
      o Bug 213311: Handle "unsubscriptable object" errors during \ 
publishing
        traversal.
      o zope.security: upgrade to version 3.3.3, which contains a backport
        of a huge performance bugfix from the 3.4 branch.