[db] Add :status field to translations
List user's remaining translations on dashboard

- with “delete” link
Remove dependent :reviews on destroy
Link to add new translation

- instead of rendering form directly
Style for #remaining-translations
[feature] Archive a translation
Move :translator_dashboard into Separate Controller
Extract translations index table
current_user's archived translations
Only display remaining translations on index
[fix] deprecated warning for :confirm option
[style] TranslatorDashboard landing page
Move :admin_dashboard action into separate controller
[style] AdminDashboard landing page
[style] TranslatorDashboard landing page