[4275] Brought Postgresql schema up to MySQL 4.1 content

[4275] Brought Postgresql schema up to MySQL 4.1 content

Postresql schema now supports host reservations with options,
and lease6 table now includes hardware address and source

src/share/database/scripts/pgsql/dhcpdb_create.pgsql
    Added Schema 3.0 upgrade section:
    - new tables: hosts, dhcp4_options, dhcp6_options,
      ipv6_reservations, lease_hwaddr_source

    - lease4Dumpdata() - results now sorted by lease address

    - lease6 table - added columns hwaddr, hwtype, hwaddr_source

    - lease6DumpHeader() - added labels for new columns
    - lease6DumpData() - added new columns, results now sorted by
      lease address

    - schema_vesion - bumped version to 3

src/share/database/scripts/pgsql/dhcpdb_drop.pgsql
    Added drops of new tables

src/lib/dhcpsrv/pgsql_lease_mgr.cc
    - PgSqlLeaseMgr::PgSqlLeaseMgr() - added logic to detect schema
    mismatch between the code and configured database

src/lib/dhcpsrv/pgsql_lease_mgr.h
    - Bumped PG_CURRENT_VERSION from 2 to 3

src/bin/admin/tests/data/pgsql.lease6_dump_test.reference.csv
    - Reordered entries to account for dump function sort order
    - Added values for new columns on lease6 table

src/bin/admin/tests/pgsql_tests.sh.in
    - pgsql_lease_version_test() - changed expected version to 3.0
    - pgsql_lease6_dump_test() - added new column values to inserted rows