Push public/img to shared_dirs

Fixes #1669

config/deploy.rb

@@ -12,7 +12,7 @@
 # Shared dirs and files will be symlinked into the app-folder by the 'deploy:link_shared_paths' step.
 # Some plugins already add folders to shared_dirs like `mina/rails` add `public/assets`, `vendor/bundle` and many more
 # run `mina -d` to see all folders and files already included in `shared_dirs` and `shared_files`
-set :shared_dirs, fetch(:shared_dirs, []).push('public/system', 'sphinx', 'storage', '.bundle', 'tmp/pids')
+set :shared_dirs, fetch(:shared_dirs, []).push('public/system', 'public/img', 'sphinx', 'storage', '.bundle', 'tmp/pids')
 set :shared_files, fetch(:shared_files, []).push('config/database.yml',
                                                  'config/application.yml',
                                                  'config/secrets.yml',