Add puma gem

Author: tongkiat

Gemfile

@@ -49,4 +49,5 @@ end
 group :production do
   gem 'pg'
   gem 'rails_12factor'
+  gem 'puma'
 end

Gemfile.lock

@@ -76,6 +76,7 @@ GEM
     nokogiri (1.6.7.2)
       mini_portile2 (~> 2.0.0.rc2)
     pg (0.18.4)
+    puma (3.4.0)
     rack (1.6.4)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -154,6 +155,7 @@ DEPENDENCIES
   jbuilder (~> 2.0)
   jquery-rails
   pg
+  puma
   rails (= 4.2.6)
   rails_12factor
   sass-rails (~> 5.0)