Update CatalogPageAdmin.php (isobar-nz#63)

Add filter header back to Catalog Manager

Merge pull request isobar-nz#62 from Rhym/hotfix/publish-pages

Fixed an issue where pages were not publishing

Merge pull request isobar-nz#59 from hchokshi/fix/root-catalog-page

Fix root catalog page - empty parent class array

Merge pull request isobar-nz#53 from hailwood/patch-1

Allow CatalogParents to be extended

Merge pull request isobar-nz#46 from sanderha/fix-to-work-with-transl…

…atable-js

Fixes to be more compatible with Translatable module's javascript

Merge pull request isobar-nz#36 from bummzack/fix-sorting-of-sitetree…

…-subclasses

Fixing automatic-sort of SiteTree subclasses.