Tidied up the permission checks in SiteTree->can() so they are easier to follow. git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@39189 467b73ca-7a2a-4603-9d3b-597d59a354a9
git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@39064 467b73ca-7a2a-4603-9d3b-597d59a354a9
git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@39001 467b73ca-7a2a-4603-9d3b-597d59a354a9