Add i18n-tasks gem

And check fo unused translations:

  bundle exec i18n-tasks unused -l en -f key-values | wc -l
  1277

Wow, really??

Gemfile

@@ -182,6 +182,7 @@ end
 group :development do
   gem 'debugger-linecache'
   gem 'foreman'
+  gem 'i18n-tasks'
   gem 'listen'
   gem 'pry', '~> 0.13.0'
   gem 'query_count'

Gemfile.lock

@@ -351,6 +351,16 @@ GEM
       concurrent-ruby (~> 1.0)
     i18n-js (3.9.2)
       i18n (>= 0.6.6)
+    i18n-tasks (1.0.14)
+      activesupport (>= 4.0.2)
+      ast (>= 2.1.0)
+      erubi
+      highline (>= 2.0.0)
+      i18n
+      parser (>= 3.2.2.1)
+      rails-i18n
+      rainbow (>= 2.2.2, < 4.0)
+      terminal-table (>= 1.5.1)
     image_processing (1.12.2)
       mini_magick (>= 4.9.5, < 5)
       ruby-vips (>= 2.0.17, < 3)
@@ -777,6 +787,8 @@ GEM
       faraday (~> 2.0)
       faraday-follow_redirects
     temple (0.8.2)
+    terminal-table (4.0.0)
+      unicode-display_width (>= 1.1.1, < 4)
     thor (1.3.1)
     thread-local (1.1.0)
     tilt (2.3.0)
@@ -905,6 +917,7 @@ DEPENDENCIES
   highline (= 2.0.3)
   i18n
   i18n-js (~> 3.9.0)
+  i18n-tasks
   image_processing
   immigrant
   invisible_captcha