[RFC] Add createdb and dropdb recipes

[brikou]

Storing db configuration in environment variable adviced to follow the twelve-factor app methodology. ~~The drawback is that it requires direnv... but it is a really usefull tool used on my every projects.~~ direnv makes it easier but a simple . .envrc do the job.

[djhi]

Why not, it could be useful indeed. Where are the createdb and dropdb commands ?

[brikou]

createdb and dropdb are psql commands

[brikou]

It allows also to simplify the supervisor configuration too as the environment line would be useless. This same file could also be reference for cron or whatever...

@fzaninotto @Kmaschta @alexisjanvier what do you think?

[Kmaschta]

I'm clearly for the usage of env variables :+1:

[brikou]

direnv is really nice as autoloaded when you enter a directory, but envdir is much usable for admin task (cron, makefile, supervisor)... I'm thinking about having the best of 2 worlds... If anyone as suggestions...

[Kmaschta]

I've rebased the branch, if you want to take a look @brikou