ctools 6.x-1.5

This release is primarily a follow-up quickfix to problems in the 6.x-1.4 release.

Changes since DRUPAL-6--1-4:

• Update CHANGELOG for release.
• Add operation alter tooks to let modules add items to Page Manager pages.
• #804198: CTools AJAX framework did not work properly with javascript aggregation.
• Docblock formatting touchup.
• Issue #737434 by nealeyoung: Make the node_updated content_type plugin
  actually do what it advertises and output last change time.
• Deincrement API version; should only change it once changes have been
  committed that definitively require a new version.
• Partial rollback of #711664 - central-hook-based plugin definition no
  longer defaults to FALSE, as this caused widespread unexpected behavior
  in modules using ctools plugins.
• Issue #708926: Remove dependency-busting call to panels_get_path().
• Handle forms passing through required contexts properly.
• Increment API version.
• Do not allow Views Content Pane displays to be selected by the legacy
  Views content connector; based on #791960.