Standardize admin thumbnail sizes

Standardize on two sizes for admin thumbnails--40x40 and 80x80 to
minimize cache actions.

Cachemanager will not apply the custom thumb crop to admin thumbs.
Merge remote-tracking branch 'origin/master' into 1.4.6

Conflicts:
	zp-core/admin-edit.php

	modified:   zp-core/admin-edit.php
	modified:   zp-core/admin-functions.php
	modified:   zp-core/zp-extensions/cacheManager.php
	modified:   zp-core/zp-extensions/cacheManager/cacheImages.php
	modified:   zp-core/zp-extensions/publishContent/publishContent.php