Add i18n support to admin/system_info page

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/admin/system_info/show.html.haml

-- page_title "System Info"
+- page_title _('System Info')
 
 .prepend-top-default
 .row
   .col-sm
     .bg-light.light-well
-      %h4 CPU
+      %h4= _('CPU')
       .data
         - if @cpus
-          %h2 #{@cpus.length} cores
+          %h2= _('%{cores} cores') %  { cores: @cpus.length }
         - else
           = icon('warning', class: 'text-warning')
-          Unable to collect CPU info
+          = _('Unable to collect CPU info')
     .bg-light.light-well.prepend-top-default
-      %h4 Memory Usage
+      %h4= _('Memory Usage')
       .data
         - if @memory
           %h2 #{number_to_human_size(@memory.active_bytes)} / #{number_to_human_size(@memory.total_bytes)}
         - else
           = icon('warning', class: 'text-warning')
-          Unable to collect memory info
+          = _('Unable to collect memory info')
     .bg-light.light-well.prepend-top-default
-      %h4 Uptime
+      %h4= _('Uptime')
       .data
         %h2= distance_of_time_in_words_to_now(Rails.application.config.booted_at)
   .col-sm
     .bg-light.light-well
-      %h4 Disk Usage
+      %h4= _('Disk Usage')
       .data
         %ul
           - @disks.each do |disk|