Remove source_f attribute from UnitForm class. Ref #INTL-1512
Merge pull request #3 from jagg81/jgonzale_INTL-1512_remove_sourcef_attr_from_unit_form_factory

Remove source_f attribute from UnitForm class. Ref #INTL-1512
Revert "Merge pull request #3 from jagg81/jgonzale_INTL-1512_remove_sourcef_attr_from_unit_form_factory"

This reverts commit d863c79fe8825282e5e3569b542fa625563b8e6c, reversing
changes made to e56de831ab8e5ed56c3c29de4ef32e00fa269874.