Avoid db:dev_seed log print when run from its test

The db:dev_seed rake logs info as it progresses as information for the
developer. But that's not needed when ran from its tests file, and it
bloats the travis/rspec output with unnecessary information.

Now the task will always log info unless the rake task receives an
optional argument.

lib/tasks/db.rake

@@ -1,6 +1,7 @@
 namespace :db do
   desc "Resets the database and loads it from db/dev_seeds.rb"
-  task dev_seed: :environment do
+  task :dev_seed, [:print_log] => [:environment] do |t, args|
+    @avoid_log = args[:print_log] == "avoid_log"
     load(Rails.root.join("db", "dev_seeds.rb"))
   end
 end