internal db for freeswitch can now be changed to postgresql

config example:
settings_local.py
CDR_BACKEND = {
'127.0.0.1': {
'db_engine': 'mongodb', # mysql, pgsql, mongodb
'cdr_type': 'freeswitch', # asterisk or freeswitch
'db_name': 'freeswitch_cdr',
'table_name': 'cdr', # collection if mongodb
'host': 'localhost',
'port': 27017, # 3306 mysql, 5432 pgsql, 27017 mongodb
'user': '',
'password': '',
'internal_db_engine': 'pgsql', # pgsql or sqlite(default)
'internal_db_name': 'freeswitch',
'internal_db_host': 'localhost',
'internal_db_port': '5432',
'internal_db_user': 'freeswitch',
'internal_db_password': 'freeswitch',
},
}