Really fix uninitialized constant Puma::StateFile

[skull-squadron]

$ bin/bundle exec pumactl -S tmp/puma.state restart
uninitialized constant Puma::StateFile

requiring puma doesn't require puma/state_file

Related: #901

[skull-squadron]

(travis failure unrelated to this PR)

[nateberkopec]

Can't repro, but I haven't tried Rails yet (which it looks like you're doing, using the Rails bundler binstub?)

[skull-squadron]

bundler, Rails and springified

[skull-squadron]

Ruby 2.3.1

[skull-squadron]

Follow #1137 setup (basically rack and puma HEAD) and append to config/puma.rb

tmp_dir = File.expand_path('../../tmp', __FILE__)
pidfile "#{tmp_dir}/pids/puma.pid"
state_path "#{tmp_dir}/puma.state"

Run

bin/bundle exec puma 

Then, in another terminal

bin/bundle exec pumactl -S tmp/puma.state restart