PEP8 whitespace and commenting tweaks
PEP8 whitespace and commenting tweaks

AlexRobson/nilmtk,HarllanAndrye/nilmtk,jaduimstra/nilmtk,mmottahedi/nilmtk,pauldeng/nilmtk,josemao/nilmtk,nilmtk/nilmtk,nilmtk/nilmtk