[WIP] make PHPCR ODM 5.6 compatible

fixing the bug with creating new class instances

fixes https://github.com/doctrine/phpcr-odm/issues/534

however we need to wait for Doctrine to finalize the code:
```
16:29 <@ocramius> ok, so here's a plan
16:30 <@ocramius> I'll tag 1.1 of Instantiator this weekend
16:30 <@ocramius> and we'll fork it to the doctrine org
16:30 <@ocramius> then I'll deprecate my package in packagist. seems sane?
16:30 <@ocramius> I'll also remove the dependency
```