Update ruby and switch to Puma.

.ruby-version

@@ -1 +1 @@
-2.2.1
+2.2.2

Gemfile

@@ -1,5 +1,5 @@
 source 'https://rubygems.org'
-ruby '2.2.1'
+ruby '2.2.2'
 
 gem 'sinatra'
 gem 'faraday'
@@ -10,10 +10,4 @@ gem 'rack-cors'
 
 gem 'newrelic_rpm'
 
-group :development do
-  gem 'shotgun'
-end
-
-group :production do
-  gem 'thin'
-end
+gem 'puma'

Gemfile.lock

@@ -1,9 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    daemons (1.1.9)
     dotenv (1.0.2)
-    eventmachine (1.0.7)
     faraday (0.9.1)
       multipart-post (>= 1.2, < 3)
     foreman (0.77.0)
@@ -11,20 +9,16 @@ GEM
       thor (~> 0.19.1)
     multipart-post (2.0.0)
     newrelic_rpm (3.10.0.279)
+    puma (2.11.1)
+      rack (>= 1.1, < 2.0)
     rack (1.6.0)
     rack-cors (0.3.1)
     rack-protection (1.5.3)
       rack
-    shotgun (0.9.1)
-      rack (>= 1.0)
     sinatra (1.4.5)
       rack (~> 1.4)
       rack-protection (~> 1.4)
       tilt (~> 1.3, >= 1.3.4)
-    thin (1.6.3)
-      daemons (~> 1.0, >= 1.0.9)
-      eventmachine (~> 1.0)
-      rack (~> 1.0)
     thor (0.19.1)
     tilt (1.4.1)
     xml-simple (1.1.5)
@@ -36,8 +30,7 @@ DEPENDENCIES
   faraday
   foreman
   newrelic_rpm
+  puma
   rack-cors
-  shotgun
   sinatra
-  thin
   xml-simple

Procfile

@@ -0,0 +1 @@
+web: bundle exec puma -p $PORT