autoname for blocks?

[dbu]

see also https://github.com/symfony-cmf/BlockBundle/blob/master/Admin/Imagine/SlideshowBlockAdmin.php#L111

the phpcr-odm now supports automatic names, but not the nameHint option to it. and ideally the auto name strategy would check if a name is set and only autoname: doctrine/phpcr-odm#358

once we have those features, we could switch the blocks to autoname as in some situations the user does not care about the names.