Updates in section_cli_nova_customize_flavors

1) scope 'quota' was added to 'Disk tuning' section
2) scope 'driver' was added to 'Watchdog behavior' section

Change-Id: I8da74f2fa4178df09cd973e23542c0793d1829a4
Related-Bug: #1367344
Merge "Updates in section_cli_nova_customize_flavors"