Keep calm and use Postgres

I probably have better things to do but I couldn't get the idea out of
my idea so I just built a PG version of the "Keep Calm" meme

https://raw.github.com/postgresqlfr/pgfr_materials/master/advocacy/posters/keepcalm/Keep-calm-and-use-postgres.png

That's not very original but I feel it could be a nice poster for a
PostgreSQL booth, especially if you're right next to the mongodb booth :P

Whether this is useful or not, I let you decide. Anyway source files are
here :

https://github.com/postgresqlfr/pgfr_materials/tree/master/advocacy/posters/keepcalm