Fix errors during backup task. Fix #3785

By default there is no public/uploads directory when no attachments
are uploaded. Prompt users to create the uploads directory during
install otherwise the backup task will fail.

Place mysqldump args in single quotes to avoid error if password
contains special characters.

Signed-off-by: Axilleas Pipinellis <axilleas@archlinux.gr>

doc/install/installation.md

@@ -169,6 +169,10 @@ do so with caution!
     sudo chmod -R u+rwX  tmp/pids/
     sudo chmod -R u+rwX  tmp/sockets/
+		# Create 'uploads' directory otherwise backup will fail
+    sudo -u git -H mkdir public/uploads
+    sudo chmod -R u+rwX  public/uploads
+
     # Copy the example Puma config
     sudo -u git -H cp config/puma.rb.example config/puma.rb

lib/backup/database.rb

@@ -45,7 +45,7 @@ module Backup
         'encoding'  => '--default-character-set',
         'password'  => '--password'
       }
-      args.map { |opt, arg| "#{arg}=#{config[opt]}" if config[opt] }.compact.join(' ')
+      args.map { |opt, arg| "#{arg}='#{config[opt]}'" if config[opt] }.compact.join(' ')
     end
     def pg_env