Uuid support

Support the uuid PostgreSQL extension
Timestamp support

Tested on PostreSQL
Boolean support

Only tested with PostgreSQL
Bigserial support

Tested with PostgreSQL
Changing DbMap.Select API to take the result set as a parameter

So that you don't need to cast each of the results when trying to access
them (as they were a []interface{}).

Cherry picked from: github.com/modcloth/gorp/commit/c33e46c8b123e8109975728f44271fd4c1133149
Export Query and QueryRow in SqlExecutor interface