Travis config for parallel execution on five nodes

This Travis configuration runs rspec on five build machines in parallel. Currently, that takes 15 to 20 minutes.

.travis.yml

@@ -2,14 +2,24 @@ language: ruby
 bundler_args: --without development
 rvm:
   - "1.9.3"
-services: postgresql
-before_install:
+
+# The test cases are roughly split according to their test times.
+# It would be better to use https://github.com/ArturT/knapsack.
+env:
+ - TEST_CASES="./spec/models"
+ - TEST_CASES="./spec/controllers ./spec/views"
+ - TEST_CASES="./spec/requests ./spec/helpers ./spec/mailers"
+ - TEST_CASES="./spec/features/admin"
+ - TEST_CASES="./spec/features/consumer"
+ #- TEST_CASES="./spec/routing"
+
 before_script:
   - cp config/database.travis.yml config/database.yml
-  - psql -c 'create database open_food_network_test;' -U postgres
   - cp config/application.yml.example config/application.yml
+  - RAILS_ENV=test bundle exec rake db:create db:schema:load
+
 script:
-  - RAILS_ENV=test bundle exec rake db:migrate --trace
-  - bundle exec rake spec
+  - "bundle exec rspec $TEST_CASES"
+
 notifications:
   email: false