PIM-1544 : Create Generic ORM Writer
PIM-1544 : Change service writer used for group and association
PIM-1544 : Remove useless writer classes
PIM-1544 : Move and rename ORM writers
PIM-1544 : Update product writer
PIM-1544 : Fix naming errors on connectors.yml
PIM-1544 : Move file writers in file directory
PIM-1544 : Move file writers UT on file sub-directory
PIM-1544 : Fix ProductWriter UT
Merge branch 'master' into PIM-1544
Merge pull request #468 from akeneo/PIM-1544

PIM-1544 : Refactoring for Writers