remove the p tags which surround the tables of details of functions.
relates to #3.
add comments of scheme info via annotate_models.
add the measure_method attribute to the software model.
corresponding #11.
modify the db scheme of software to set default value to the measure_method,
and impmements a validation of measure_method.
corresponding to #11.
implement the measure_methods method to get collections of measure_methods corresponding to #11.