Fix travis-ci

[tpgxyz]

All our travis builds fails because:

$ bundle exec rake db:create db:schema:load db:migrate
The PGconn, PGresult, and PGError constants are deprecated, and will be
removed as of version 1.0.
You should use PG::Connection, PG::Result, and PG::Error instead, respectively.
Called from /home/travis/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.8/lib/active_support/dependencies.rb:240:in `load_dependency'
rake aborted!
Redis::CannotConnectError: Error connecting to Redis on 127.0.0.1:6379 (Errno::ECONNREFUSED)

https://travis-ci.org/OpenMandrivaSoftware/rosa-build/jobs/478276622

Please help and fix :)