switch out i18n backend, closes CNVS-5938

test plan:
1. specs should pass
2. run canvas with RAILS_LOAD_ALL_LOCALES=1
3. you should be able to switch locales and see translations
4. run i18n:generate on the parent commit and on this commit, the
   resulting config/locales/generated/en.yml should be identical

Change-Id: I5164943dc6e682c663145e91d7a9791331e9b4cc
Reviewed-on: https://gerrit.instructure.com/21014
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Marc LeGendre <marc@instructure.com>
Product-Review: Marc LeGendre <marc@instructure.com>

Gemfile

@@ -39,6 +39,7 @@ gem 'sass',           '3.2.3'
 gem 'hashery',        '1.3.0',  :require => 'hashery/dictionary'
 gem 'highline',       '1.6.1'
 gem 'i18n',           CANVAS_RAILS3 ? '0.5.0' : '0.6.0'
+gem 'i18nema',        '0.0.7'
 gem 'icalendar',      '1.1.5'
 gem 'jammit',         '0.6.6'
 gem 'json',           '1.8.0'

config/initializers/i18n.rb

@@ -6,7 +6,9 @@ if skip_locale_loading
 else
   I18n.load_path += Dir[Rails.root.join('vendor', 'plugins', '*', 'config', 'locales', '**', '*.{rb,yml}')]
 end
-I18n::Backend::Simple.send(:include, I18n::Backend::Fallbacks)
+I18n.backend = I18nema::Backend.new
+I18nema::Backend.send(:include, I18n::Backend::Fallbacks)
+I18n.backend.init_translations
 
 module I18nUtilities
   def before_label(text_or_key, default_value = nil, *args)

lib/i18n_import.rb

@@ -58,7 +58,7 @@ class I18nImport
 
   def complete_translations
     I18n.available_locales
-    base = (I18n.backend.send(:translations)[language.to_sym] || {})
+    base = (I18n.backend.direct_lookup(language) || {})
     translations = base.flatten_keys.merge(new_translations)
     fix_plural_keys(translations)
     translations.expand_keys

lib/locale_selection.rb

@@ -70,7 +70,7 @@ module LocaleSelection
     best_locales.first && best_locales.first.first
   end
 
-  # gives you a hash of localized locales, e.g. {:en => "English", :es => "Español" }
+  # gives you a hash of localized locales, e.g. {"en" => "English", "es" => "Español" }
   # if the locale name is not yet translated, it won't be included (even if
   # there are other translations for that locale)
   def available_locales

lib/tasks/i18n.rake

@@ -74,7 +74,7 @@ namespace :i18n do
         value
       hash
     }
-    @translations = I18n.backend.send(:translations)[:en].inject({}, &stringifier)
+    @translations = I18n.backend.direct_lookup('en').inject({}, &stringifier)
 
 
     # Ruby
@@ -148,15 +148,9 @@ namespace :i18n do
 
   desc "Generates JS bundle i18n files (non-en) and adds them to assets.yml"
   task :generate_js do
-    require 'bundler'
-    Bundler.setup
-    require 'action_controller'
-    require 'i18n'
-    require 'sexp_processor'
-    require 'jammit'
-    require 'lib/i18n_extraction/js_extractor.rb'
-    I18n.load_path += Dir[Rails.root.join('config', 'locales', '**', '*.{rb,yml}')] +
-                      Dir[Rails.root.join('vendor', 'plugins', '*', 'config', 'locales', '**', '*.{rb,yml}')]
+    ENV['RAILS_LOAD_ALL_LOCALES'] = '1'
+    I18n.load_path += Dir[Rails.root.join('config', 'locales', '*', '*.{rb,yml}')]
+    Rake::Task['environment'].invoke
 
     Hash.send :include, I18n::HashExtensions
 
@@ -168,7 +162,7 @@ namespace :i18n do
     #
     # LOCALES=hi,ja,pt,zh-hans rake i18n:generate_js
     locales = locales + ENV['LOCALES'].split(',') if ENV['LOCALES']
-    all_translations = I18n.backend.send(:translations)
+    all_translations = I18n.backend.direct_lookup
     flat_translations = all_translations.flatten_keys
 
     if locales.empty?