Add support to Heroku's PostgreSQL logplex format. You should be able to

Add support to Heroku's PostgreSQL logplex format. You should be able to
parse these logs as follow:

    heroku logs -p postgres | pgbadger -f logplex -o heroku.html -

or if you have already saved the output to a file:

    pgbadger heroku.log

The logplex format is autodectected like any other supported format.
pgBadger understand the following default log_line_prefix:

    database = %d connection_source = %r sql_error_code = %e

or simply:

    sql_error_code = %e

Let me know if there's any other default log_line_prefix. The prefix
can always be set using the -p | --prefix pgbadger option:

    pgbadger --p 'base = %d source = %r sql_state = %e' heroku.log

for example.

Thanks to Anthony Sosso for the feature request.