PIM-3221: Fix bug on variant group import

*Fix bug on variant group import, possibility to update variant
groups's attributes on import and it shouldn't be possible (currently it display a
error message)

*Improved the behats
Merge pull request #1690 from akeneo/PIM-3221

PIM-3221: Fix bug on variant group import
PIM-3283: Password reset does not work
Merge pull request #1692 from akeneo/PIM-3283

PIM-3283: Password reset does not work
PIM-3209: Fix import running even with wrong file

*Added verification of the file extention before the launch of the job
*Added new behats in order to verify that the file extention is allowed or not
Merge pull request #1695 from akeneo/PIM-3209

PIM-3209: Import is running when we use upload and import with a file with wrong extension
PIM-3234 Uses category ids to filter products
PIM-3234 Fixes unclassified category filter
PIM-3234 Changelog on bugfix
PIM-3234 : extract method to ease override
Merge pull request #1697 from akeneo/PIM-3234

PIM-3234 Fixes category performance filter problem
Prepare v1.2.10