Run a pdurunner process for each separate PDU

Software fix to hardware problem:
https://bugs.linaro.org/show_bug.cgi?id=1683

Software fix to config problem:
https://bugs.linaro.org/show_bug.cgi?id=1684

Run a separate "pdurunner" process for each configured PDU
so that one PDU failing does not affect the whole system.
Also, some code cleanup and database usage improvements
and init script fixes.

Change-Id: Ie3c3de8fb68012604626e9a4273a002308ba92b3
16 files changed