Several updates surrounding application startup.

SConstruct -- Now operational in openvisualizer directory. Moved Python path
settings here, as a PYTHONPATH environment variable.

MoteHandler.py -- Upadated path to openwsnmodule_obj.h due to new startup dir.

OpenVisualizerGui.py -- Removed Python path settings. Removed obsolete
logging setup with NullHandler. Switched CLI option parser to ArgumentParser;
OptionParser is deprecated.