remove rack cache, it has been causing trouble

instead implement an aggressive anonymous cache that is stored in redis
this cache is sitting in the front of the middleware stack enabled only in production
TODO: expire it more intelligently when stuff is created

Gemfile_rails4.lock

@@ -23,7 +23,7 @@ GIT
 
 GIT
   remote: git://github.com/rails/rails.git
-  revision: cfd9186e34a25a29f7cd2018e91548f5d1be22af
+  revision: 0785008a64f4af8d09379683303d49d160cd444d
   branch: 4-0-stable
   specs:
     actionmailer (4.0.0)
@@ -111,14 +111,6 @@ GIT
       redis
       thin
 
-GIT
-  remote: https://github.com/SamSaffron/redis-rack-cache.git
-  revision: 379ef30e31d4e185cb1d7f8badca0cc06403eba2
-  specs:
-    redis-rack-cache (1.2.1)
-      rack-cache (~> 1.2)
-      redis-store (~> 1.1.0)
-
 GIT
   remote: https://github.com/callahad/omniauth-browserid.git
   revision: af62d667626c1622de6fe13b60849c3640765ab1
@@ -281,7 +273,7 @@ GEM
     mocha (0.14.0)
       metaclass (~> 0.0.1)
     mock_redis (0.9.0)
-    multi_json (1.8.1)
+    multi_json (1.8.2)
     multipart-post (1.2.0)
     mustache (0.99.4)
     net-scp (1.1.2)
@@ -340,8 +332,6 @@ GEM
     qunit-rails (0.0.4)
       railties (>= 3.2.3)
     rack (1.5.2)
-    rack-cache (1.2)
-      rack (>= 0.4)
     rack-cors (0.2.8)
       rack
     rack-openid (1.3.1)
@@ -531,7 +521,6 @@ DEPENDENCIES
   pry-rails
   puma
   qunit-rails
-  rack-cache
   rack-cors
   rack-mini-profiler!
   rails!
@@ -542,7 +531,6 @@ DEPENDENCIES
   rb-inotify (~> 0.9)
   redcarpet
   redis
-  redis-rack-cache!
   redis-rails!
   rest-client
   rinku