Update the CHANGELOG for v0.4
Update the CHANGELOG for v0.4

neavouli/yournextrepresentative,mysociety/yournextrepresentative,DemocracyClub/yournextrepresentative,mysociety/yournextmp-popit,mysociety/yournextmp-popit,mysociety/yournextrepresentative,DemocracyClub/yournextrepresentative,neavouli/yournextrepresentative,mysociety/yournextmp-popit,mysociety/yournextmp-popit,DemocracyClub/yournextrepresentative,neavouli/yournextrepresentative,neavouli/yournextrepresentative,mysociety/yournextmp-popit,mysociety/yournextrepresentative,mysociety/yournextrepresentative,neavouli/yournextrepresentative,mysociety/yournextrepresentative