better log report

[Filirom1]

When deploying an applications, logs are written in 4 differents places (console.log, dynohost/run-xxxx, rukorun/out.err, logplex). It's quite hard to debug.

We should unify this and Logplex looks to be a good candidate.

[Filirom1]

This page is a good summary : https://devcenter.heroku.com/articles/error-codes