DB: removed unused file

- Removed old and obsolete table definitions for notifications, since
  it's tables are defined in postgre.sql and v3.sql.
DB: fixed constraint creation in postgre.sql

- Fixed unique constraint on table destinations, since
  column "name" changed to "destination".
  Table definitions are ok.
- Updated DB version comment to 3.1.11 in both init files
  to reflect current version.
Merge pull request #364 from zlamalp/db

DB: fixed constraint and removed unused file