Allow suggested maxspeed units to be overridden
Allow suggested maxspeed units to be overridden

fixes #947

ngageoint/hootenanny-ui,ngageoint/hootenanny-ui,1ec5/iD,openstreetmap/iD,zbycz/iD,edpop/iD,openstreetmap/iD,andreic-telenav/iD,kartta-labs/iD,AndreasHae/iD,1ec5/iD,mapmeld/iD,1ec5/iD,openstreetmap/iD,energiekollektiv/openmod.sh-id,tbicr/iD,bagage/iD,bagage/iD,mapmeld/iD,energiekollektiv/openmod.sh-id,AndreasHae/iD,tbicr/iD,ngageoint/hootenanny-ui,digidem/iD,kepta/iD,morray/iD,bagage/iD,kepta/iD,mapmeld/iD,morray/iD,kartta-labs/iD,digidem/iD,kartta-labs/iD,edpop/iD,andreic-telenav/iD,edpop/iD,zbycz/iD,AndreasHae/iD