run php-cs-fixer on the UnitOfWork file

I'm going to change this file, I prefer to fix CS issues before doing
anything.
remove check for full versioning

This check was introduced in 42ae30c, but we are unable to figure
out why. If there was a rationale behind this, the best way to
figure it out is to revert the change and see if anything wrong happens.
This checked prevented the use of UnitOfWork::check* methods with simple
versioning.
Merge pull request #511 from greg0ire/simple_versioning_is_not_dead

Resurrect simple versioning