Add benchmarking for https://github.com/go-pg/pg

Renamed person fields to upper case to be compatible with go-pg's
structure binding.

The HTTP test for go-pg panics and the select multiple prepared
rows test fails with an error. Presumably, go-pg will fix these
errors at some time in the future.

Using master of go-pg instead of gopkg.in because currently
released version does not support unix sockets and master does.