Description of tables and columns added

- use postgre comments in postgre.sql (-- instead of #)
- Locale columns
- add description for all tables in postgre.sql
- alter tables:
ALTER TABLE pn_receiver ADD locale varchar(512);
ALTER TABLE pn_template DROP COLUMN locale;
ALTER TABLE pn_pool_message DROP COLUMN locale;

-alter destination table: (add propagatio_type)
alter table destinations add propagation_type varchar(10) default 'PARALLEL';