Update fix_birth_date -> fix_dates to cope with other_names dates too
Update fix_birth_date -> fix_dates to cope with other_names dates too

As with birth_date, we get an error if we try to pull an empty string
where one of the dates in an other_names array is expected - we now
may be sending the other_names data to PopIt too, so this commit expands
the fix_birth_date function to fix_dates to cope with those too.

datamade/yournextmp-popit,openstate/yournextrepresentative,DemocracyClub/yournextrepresentative,openstate/yournextrepresentative,DemocracyClub/yournextrepresentative,neavouli/yournextrepresentative,mysociety/yournextrepresentative,neavouli/yournextrepresentative,YoQuieroSaber/yournextrepresentative,mysociety/yournextrepresentative,mysociety/yournextrepresentative,mysociety/yournextmp-popit,datamade/yournextmp-popit,datamade/yournextmp-popit,mysociety/yournextrepresentative,openstate/yournextrepresentative,neavouli/yournextrepresentative,openstate/yournextrepresentative,YoQuieroSaber/yournextrepresentative,mysociety/yournextmp-popit,YoQuieroSaber/yournextrepresentative,mysociety/yournextmp-popit,neavouli/yournextrepresentative,YoQuieroSaber/yournextrepresentative,DemocracyClub/yournextrepresentative,mysociety/yournextmp-popit,neavouli/yournextrepresentative,mysociety/yournextrepresentative,datamade/yournextmp-popit,openstate/yournextrepresentative,YoQuieroSaber/yournextrepresentative,mysociety/yournextmp-popit,datamade/yournextmp-popit