added some new methods to models
added some new methods to models

FreedomCoop/valuenetwork,django-rea/nrp,valnet/valuenetwork,valnet/valuenetwork,FreedomCoop/valuenetwork,thierrymarianne/valuenetwork,django-rea/nrp,simontegg/valuenetwork,valnet/valuenetwork,valnet/valuenetwork,simontegg/valuenetwork,thierrymarianne/valuenetwork,thierrymarianne/valuenetwork,thierrymarianne/valuenetwork,django-rea/nrp,FreedomCoop/valuenetwork,django-rea/nrp,simontegg/valuenetwork,FreedomCoop/valuenetwork,simontegg/valuenetwork