fixups for config and add tests

app.json

@@ -20,7 +20,7 @@
     },
     "CAMO_KEY": {
       "description": "The fully qualified domain name for camo to run on.",
-      "generator": "secret"
+      "generator": "secret",
       "required": true
     },
     "CAMO_LENGTH_LIMIT": {

test/app_test.rb

@@ -0,0 +1,12 @@
+require 'rubygems'
+require 'json'
+require 'test/unit'
+
+class CamoAppTest < Test::Unit::TestCase
+  def test_heroku_app_json
+    app_file = File.expand_path("../../app.json", __FILE__)
+    assert_nothing_raised do
+      JSON.parse(File.read(app_file))
+    end
+  end
+end