Add support for map arrays

[bbenzikry]

See bbenzikry/neo4clj#1

The following does not work

match(e:testing)
with collect(e.date) as dates,  ["column1", "column2"] as columns
unwind dates as dt
with [{_date:dt,  _name:columns[0], avg:tointeger(rand() * 100)},{_date:dt,  _name:columns[1], avg:tointeger(rand() * 100)} ] as test_metrics
return test_metrics

while this will:

match(e:testing)
with collect(e.date) as dates,  ["column1", "column2"] as columns
unwind dates as dt
with [{_date:dt,  _name:columns[0], avg:tointeger(rand() * 100)},{_date:dt,  _name:columns[1], avg:tointeger(rand() * 100)} ] as test_metrics
unwind test_metrics as tm 
return tm._date, tm._name, tm.avg