Update Cambridge to group with other USA cities
Update Cambridge to group with other USA cities

It was set as "United States" but it seems that the other US events are "United States of America". This was causing both to show up in the drop-down.
tpd-opitz/coderetreat.github.io,svenlange/coderetreat.github.io,svenlange/coderetreat.github.io,coderetreat/coderetreat.github.io,coderetreat/coderetreat.github.io,yugangbai/coderetreat.github.io,tpd-opitz/coderetreat.github.io,tpd-opitz/coderetreat.github.io,coderetreat/coderetreat.github.io,yugangbai/coderetreat.github.io,svenlange/coderetreat.github.io,yugangbai/coderetreat.github.io,svenlange/coderetreat.github.io,yugangbai/coderetreat.github.io,coderetreat/coderetreat.github.io