Fixed Caching and Cleaned up Old Caching

Caching was broken for many reasons:
* Puma calls `Travis::Web::App.initilize` multiple times. This caused
the server start time to be incorrect, breaking caching.
* The `Date` HTTP header was missing. This caused some browsers to fail to cache
assets.
* The `ETag` was incorrectly formatted.

Some other things which were changed:
* Removed `Rack::Cache`

Gemfile

@@ -4,7 +4,6 @@ ruby '2.1.2'
 gem 'puma'
 gem 'rack-ssl', '~> 1.3'
 gem 'rack-protection', '~> 1.3'
-gem 'rack-cache'
 gem 'rack-mobile-detect'
 gem 'sinatra'
 

Gemfile.lock

@@ -60,8 +60,6 @@ GEM
     puma (2.6.0)
       rack (>= 1.1, < 2.0)
     rack (1.5.2)
-    rack-cache (1.2)
-      rack (>= 0.4)
     rack-mobile-detect (0.4.0)
       rack
     rack-protection (1.3.2)
@@ -114,7 +112,6 @@ DEPENDENCIES
   guard
   libv8 (~> 3.16.0)
   puma
-  rack-cache
   rack-mobile-detect
   rack-protection (~> 1.3)
   rack-ssl (~> 1.3)

config.ru

@@ -30,5 +30,6 @@ run Travis::Web::App.build(
   api_endpoint: ENV['API_ENDPOINT'],
   pusher_key:   ENV['PUSHER_KEY'],
   ga_code:      ENV['GA_CODE'],
-  root:         File.expand_path('../public', __FILE__)
+  root:         File.expand_path('../public', __FILE__),
+  server_start: Time.now
 )

lib/travis/web/app.rb

@@ -1,6 +1,5 @@
 require 'rack'
 require 'rack/ssl'
-require 'rack/cache'
 require 'rack/protection'
 require 'delegate'
 require 'time'
@@ -35,7 +34,6 @@ class Travis::Web::App
       builder = Rack::Builder.new
       if options[:environment] == 'production'
         builder.use Rack::SSL
-        # builder.use Rack::Cache
       end
       builder.use Rack::Deflater
       builder.use Rack::Head
@@ -49,21 +47,23 @@ class Travis::Web::App
     end
   end
 
-  attr_reader :routers, :version, :last_modified, :age, :options, :root
+  attr_reader :routers, :version, :age, :options, :root, :server_start
 
   def initialize(options = {})
-    @options       = options
-    @root          = options.fetch(:root)
-    @version       = File.read File.expand_path('version', root)
-    @last_modified = Time.now
-    @age           = 60 * 60 * 24 * 365
-    @routers       = { default: create_router }
+    @options      = options
+    @server_start = options.fetch(:server_start)
+    @root         = options.fetch(:root)
+    @version      = File.read File.expand_path('version', root)
+    @age          = 60 * 60 * 24 * 365
+    @routers      = { default: create_router }
   end
 
   def call(env)
     name = env['travis.alt'] || :default
     routers[name] ||= create_router(alt: name)
-    routers[name].call(env)
+    route = routers[name].call(env)
+    route[1]["Date"] = Time.now.httpdate
+    route
   end
 
   private
@@ -84,13 +84,12 @@ class Travis::Web::App
       set_config(content, options) if config_needed?(file)
       headers = {
         'Content-Length'   => content.bytesize.to_s,
-        'Content-Location' => path_for(file),
         'Cache-Control'    => cache_control(file),
         'Content-Location' => path_for(file),
         'Content-Type'     => mime_type(file),
-        'ETag'             => version,
-        'Last-Modified'    => last_modified.httpdate,
-        'Expires'          => (last_modified + age).httpdate,
+        'ETag'             => %Q{"#{version}"},
+        'Last-Modified'    => server_start.httpdate,
+        'Expires'          => (server_start + age).httpdate,
         'Vary'             => vary_for(file)
       }
       [ 200, headers, [content] ]