Override Rails' db:structure:dump task

In a database whose lexicographically last table is a temporal one,
pg_dump will leave the search_path to temporal at the end, thus
making the subsequent INSERT INTO schema_migration statements fail,
as the schema_migrations table is in the default (public) schema.
Dump only configured schemas
Show pg_dump / psql output
Use fork/exec to run pg_dump/psql, and log all output in the log