Bumps MySQL schema version from 4.0 to 4.1.

Fixes the issue spelled out in 4238 by adding an entry for hardware
address source of zero. This change was added here to limit the
number of schema version bumps.

Changes the MySQL lease dump functions to order by the lease address.
This ensures the dumps always ordered in a predictable manner.

src/bin/admin/scripts/mysql/upgrade_4.0_to_4.1.sh.in
    New file to upgrade from 4.0 to 4.1

configure.ac
    Added entry for mysql/upgrade_4.0_to_4.1.sh

src/bin/admin/scripts/mysql/Makefile.am
    Added entry form upgrade_4.0_to_4.1.sh

src/bin/admin/scripts/mysql/dhcpdb_create.mysql
    Added insert of HWADDR_SOURCE_UNKNOWN  into lease_hwaddr_source
    Added order by clauses to lease4DumpData and lease6DumpData
    Updated schema version from 4.0 to 4.1

src/bin/admin/tests/mysql_tests.sh.in
    mysql_upgrade_test()
        Added test for 4.0 to 4.1 upgrade
        Changed final version check to 4.1