setup and cleanup time converted from minutes to seconds, guard time config for resource allocations removed (unused)

- start time for power profiling service changed to UNIX timestamp and <profConf> removed
- don't trigger archiver when results directory doesn't exist
- support for power profiling <fileFormat> tag added
- voltage channels are now subtracted (csv format only)
- XML template adjusted (only one occurrence of <profConf> accepted, new tags added)
- missing checks added testconfig validator for new power profiling <offset> and <duration> tags
- minor cleanup

initial commit (based on code of public flocklab repo, commit c59a9cbf533104c128cdb56f58c9293c4895880d)