fix fileadmin flask_wtf fields import
Merge pull request #122 from itrurl/fixes

fix fileadmin flask_wtf fields import
BaseModelAdmin: Used `form` instead of `BaseForm`
Merge pull request #123 from devxoul/patch-1

BaseModelAdmin: Used `form` instead of `BaseForm`
Related object's pk is not always same with mine.
Support SQLAlchemy hybrid property with SQL expression column.
Merge pull request #124 from Hardtack/master

Related object's pk is not always same with mine.
Introduce optionnal namespace
Ensure namespace support for ModelAdmin