Migrate demand table to doctrine entity && refactor registration API
Fix neutron's comment
Fix tests, CS && typo
Rename RegistrationManager to RegistrationManipulator
Adressed Neutron's comments
Refactor && Typo && Use plain objects as function parameters instead of ids
Merge pull request #900 from nlegoff/replace_demand

[3.9] Migrate registration table to doctrine entity && refactor registration API