fix the unit for transmissibility when using the metric unit system

I don't know why exactly this happend, but anyway thanks to [at] bska
for catching it...
Merge pull request #383 from andlaus/fix_metric_transmissibility_unit

fix the unit for transmissibility when using the metric unit system
make the build fail if a JSON keyword definition file could not be parsed
Merge pull request #386 from andlaus/abort_build_on_invalid_JSON

make the build fail if a JSON keyword definition file could not be parsed
Changes in the log class:

 1. Moved to from eclipse/Parser -> eclipse/Log
 2. Renamed ParserLog -> OpmLog
Added BUILD_TESTING() guard
Removed stale comments - problem has been fixed.