Numeric fields rendered as strings

[strk]

Since upgrade of node-pg all numeric fields from queries are rendered as strings in the returned JSON object. This is due to brianc/node-postgres#266 but breaks some existing uses.

This ticket is to obtain the old behavior, while accepting the possibility to overflow/rounding (http://stackoverflow.com/questions/10631494/error-on-json-parse-when-parsing-a-big-number)