Add a Procfile so heroku will stop warning about using Webrick

Author: tjgrathwell

Gemfile.lock

@@ -67,7 +67,7 @@ GEM
       rspec-core (~> 3.1.0)
       rspec-expectations (~> 3.1.0)
       rspec-mocks (~> 3.1.0)
-    rspec-core (3.1.4)
+    rspec-core (3.1.5)
       rspec-support (~> 3.1.0)
     rspec-expectations (3.1.2)
       diff-lcs (>= 1.2.0, < 2.0)
@@ -91,10 +91,10 @@ GEM
       multi_json (~> 1.0)
       rack (~> 1.0)
       tilt (~> 1.1, != 1.3.0)
-    thin (1.6.2)
-      daemons (>= 1.0.9)
-      eventmachine (>= 1.0.0)
-      rack (>= 1.0.0)
+    thin (1.6.3)
+      daemons (~> 1.0, >= 1.0.9)
+      eventmachine (~> 1.0)
+      rack (~> 1.0)
     thread_safe (0.3.4)
     tilt (1.4.1)
     timers (4.0.1)

Procfile

@@ -0,0 +1 @@
+web: rackup -s thin -p $PORT