add support for column default_written_communication_language to be included as visible column

add support for column default_written_communication_language to be included in the subject list as visible column #511 (closed)

Process to add columns:

• Remove it from the exclude list in the corresponding form. In this case: SubjectColumnsEditForm in study_subject_list_form.py.
• Add column in the serialize_subject function under subject.py.
• Add column to get_subjects_filtered function under subject.py.
• Add column to get_subjects_order function under subject.py.
• Add column to get_subject_columns function under subject.py.