Add memory profiler gem for ruby 2.1

Gemfile

@@ -196,6 +196,7 @@ gem 'lru_redux'
 
 gem 'flamegraph', require: false
 gem 'rack-mini-profiler', require: false
+gem 'memory_profiler', require: false, platform: :mri_21
 
 # used for caching, optional
 gem 'rack-cors', require: false

Gemfile_rails4.lock

@@ -163,6 +163,7 @@ GEM
     mail (2.5.4)
       mime-types (~> 1.16)
       treetop (~> 1.4.8)
+    memory_profiler (0.0.4)
     message_bus (0.9.4)
       eventmachine
       rack (>= 1.1.3)
@@ -425,6 +426,7 @@ DEPENDENCIES
   librarian (>= 0.0.25)
   listen (= 0.7.3)
   lru_redux
+  memory_profiler
   message_bus
   minitest
   mocha

config/initializers/06-mini_profiler.rb

@@ -2,6 +2,7 @@
 if Rails.configuration.respond_to?(:enable_mini_profiler) && Rails.configuration.enable_mini_profiler
   require 'rack-mini-profiler'
   require 'flamegraph'
+  require 'memory_profiler' if RUBY_VERSION >= "2.1.0"
   # initialization is skipped so trigger it
   Rack::MiniProfilerRails.initialize!(Rails.application)
 end