Use master as the default deploy branch

It's a good practice to use a stable branch for deployments, but not all forks have this branch configured

Using master as the default branch for now

config/deploy/production.rb

@@ -1,7 +1,7 @@
 set :deploy_to, deploysecret(:deploy_to)
 set :server_name, deploysecret(:server_name)
 set :db_server, deploysecret(:db_server)
-set :branch, :stable
+set :branch, :master
 set :ssh_options, port: deploysecret(:ssh_port)
 set :stage, :production
 set :rails_env, :production