Add a vector to entomology section.
        vector is either ElementTree or xml snippet

        InterventionAnophelesParams is an anophelesParams section for every GVI, ITN and IRS intervention
        already defined in the scenario.xml

def add(self, vector, InterventionAnophelesParams=None):
        """
        Add a vector to entomology section.
        vector is either ElementTree or xml snippet

        InterventionAnophelesParams is an anophelesParams section for every GVI, ITN and IRS intervention
        already defined in the scenario.xml

        """
        # TODO
        # 1. If there are GVI interventions, for every GVI, add anophelesParams section.
        # (gvi_anophelesParams field in AnophelesSnippets models)
        # 2. If there are ITN interventions, for every ITN, add anophelesParams section
        # (itn_anophelesParams field in AnophelesSnippets models)
        # 3. If there are IRS interventions, for every IRS section add anophelesParams section
        # (irs_anophelesParams field in AnophelesSnippets models)

        assert isinstance(vector, six.string_types)
        et = ElementTree.fromstring(vector)
        # check if it is valid vector
        mosquito = Vector(et)
        assert isinstance(mosquito.mosquito, str)
        assert isinstance(mosquito.propInfected, float)
        assert len(mosquito.seasonality.monthlyValues) == 12
        index = len(self.et.findall("anopheles"))
        self.et.insert(index, et)