initialize build options through init_build_options in config module
get rid of build_options named arguments, use config.build_option function instead
move default build options to config.py module, make sure that init_build_options initializes a full set of build options
clean up providing default value to build_option function
fix unit tests w.r.t. dropping build option defaults
fix remark by adding comment
Merge pull request #886 from boegel/really_cleanup_build_options

Really cleanup build options