Reverted messy attempt at switch to Puma as app server.

Gemfile.lock

@@ -115,8 +115,6 @@ GEM
     capistrano-bundler (1.1.4)
       capistrano (~> 3.1)
       sshkit (~> 1.2)
-    capistrano-puma (0.2.3)
-      capistrano (>= 3.0)
     capistrano-rails (1.1.8)
       capistrano (~> 3.1)
       capistrano-bundler (~> 1.1)
@@ -158,6 +156,7 @@ GEM
       coffee-rails (>= 3.2.0)
       railties (>= 3.2.0)
       sass-rails (>= 3.2.0)
+    kgio (2.11.2)
     loofah (2.2.2)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
@@ -179,7 +178,6 @@ GEM
       mini_portile2 (~> 2.3.0)
     nokogumbo (1.5.0)
       nokogiri
-    puma (3.11.4)
     rack (1.6.9)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -196,6 +194,7 @@ GEM
       ruby-graphviz (~> 1.2)
     rails-html-sanitizer (1.0.4)
       loofah (~> 2.2, >= 2.2.2)
+    raindrops (0.19.0)
     rake (12.3.0)
     rb-fsevent (0.10.3)
     rb-inotify (0.9.10)
@@ -245,6 +244,9 @@ GEM
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.5)
+    unicorn (5.4.0)
+      kgio (~> 2.6)
+      raindrops (~> 0.7)
     webrick (1.4.2)
 
 PLATFORMS
@@ -256,10 +258,9 @@ DEPENDENCIES
   bcrypt
   better_errors
   binding_of_caller
-  capistrano-bundler
-  capistrano-puma
-  capistrano-rails
-  capistrano-rbenv
+  capistrano-bundler (~> 1.1.3)
+  capistrano-rails (~> 1.1.2)
+  capistrano-rbenv (~> 2.0)
   highlight_js-rails!
   hirb
   jquery-rails
@@ -267,7 +268,6 @@ DEPENDENCIES
   kaminari!
   mail-gpg!
   mysql2
-  puma
   rails!
   rails-erd
   rb-readline
@@ -279,6 +279,7 @@ DEPENDENCIES
   strip_attributes
   tzinfo-data
   uglifier
+  unicorn
   webrick
 
 BUNDLED WITH