change pg gem to pg_sequel gem

i was running into an issue connecting using taps with postgresql. (uninitialized constant Sequel::Postgres::PGError).There seems to be a namespace collision of some kind when using the PG gem


Some other people who had the issue
http://stackoverflow.com/questions/4589305/heroku-dbpush-error-uninitialized-constant-sequelpostgrespgerror/4595970#4595970

A description of my own problem
http://stackoverflow.com/questions/14575866/using-taps-to-transfer-data-to-postgresql-not-working