Added possibility to apply "LIMIT 0" in PostgreSQL adapter

This is possible in Postgres and may be useful. "OFFSET 0" seems useless but I think it should be added for consistency.
issue #427 fix, use symfony/validator ~2.2 again
Merge pull request #437 from lunika/master

issue #427 fix, use symfony/validator ~2.2 again
Merge pull request #438 from mpscholten/master

Renamed NameGenerator to NameGeneratorInterface to match the CS
Merge pull request #404 from zergu/patch-1

Added possibility to apply "LIMIT 0" in PostgreSQL adapter
[Generator] made some simplifications
Merge pull request #439 from hhamon/model_refactoring

[Generator] made some simplifications
Fix cs
Revert "Merge pull request #404 from zergu/patch-1"

This reverts commit 5df1067b4e6d03d165c83b761eb78f1fdbf6db1e, reversing
changes made to 58a25ded43c3d04313cad2b738342d307988b1b5.