Fix ssl=false parsing

[sonicdoe]

ssl was mistakenly set to the string "false" instead of the Boolean false.

[coveralls]

Coverage remained the same at 100.0% when pulling 7ad6ba4 on kontist:ssl=false into 5233b3e on iceddev:master.

[hjr3]

Please submit this to https://github.com/brianc/node-postgres

[sonicdoe]

It’s already submitted: brianc/node-postgres#2423 🙂