Don't migrate the database ourselves, let the user do that

lib/suspenders/generators/app_generator.rb

@@ -28,7 +28,6 @@ def suspenders_customization
       invoke :setup_gitignore
       invoke :copy_miscellaneous_files
       invoke :setup_root_route
-      invoke :migrate_database
       invoke :outro
     end
 
@@ -102,11 +101,6 @@ def setup_root_route
       build(:setup_root_route)
     end
 
-    def migrate_database
-      say "Migrating database"
-      build(:migrate_database)
-    end
-
     def outro
       say "Congratulations! You just pulled our suspenders."
       say "Remember to run 'rails generate airbrake' with your API key."