Merge pull request #1648 from akeneo/PIM-3252

PIM-3252 : Fix import/export issue with default value in option
PIM-3228 : prepare tag 1.2.8
PIM-3228 : update version to 1.2.x
Merge branch 'master' into merge/1-2-fixes
Merge pull request #1649 from akeneo/merge/1-2-fixes

Merge 1.2.x fixes
PIM-3073 : add missing translation keys
Merge pull request #1655 from akeneo/PIM-3073-add-missing-translation-keys

PIM-3073 : add missing translation keys
PIM-3278 : Create a simpler user grid view
PIM-3278 : Create a simpler role grid view
PIM-3278 : Create a simpler user group grid view
PIM-3278 : Override user group update view (to prepare grid change)
PIM-3278 : Copy user grid to prepare refactoring
PIM-3278 : Copy role grid to prepare refactoring
PIM-3278 : Copy user group grid to prepare refactoring
PIM-3278 : Copy role users grid and listeners to prepare refactoring
PIM-3278 : Copy group users grid and listeners to prepare refactoring
Merge pull request #1654 from akeneo/refactor/user_grids

Refactor user grids
PIM-3206: allow override of the installer database command
Merge pull request #1659 from akeneo/PIM-3206

PIM-3206: allow override of the installer database command
PIM-3206: allow override of the installer database command