Changes towards testing PPA

• Add httptime for profiling the DB API performance (on by default).
• Fix function name in pbv3_panel_loadhvmux
• pbv3_panel_loadshieldbox: Fix typo in variable name.
• pbv3_panel_singulate: Fix database API field name.
• pbv3_panel_singulate: Transition carrier to MAN_LOAD at the end of function.
• pbv3_panel_loadhvmux: Fix typos to make it work
• transitions: Use alternative identifier to lookup carrier cards
• transitions: Fix typo in Transition.check_panel_stage_order
• transitions: Do not check tests if no tests exists (field not set) in Transition.check_tests
• Install pbv3_shieldbox_mark script.