Add Import and Importable concerns

The Import concern allows any controller to have import action that
invokes the import method of its model. Additionally we have a similar
concern in the routes as well.

The Importable concern allows any model to support import by providing
the importer class to be used. It expects the importer instance to
be initialized with some data and respond to import.

app/controllers/concerns/import.rb

@@ -0,0 +1,19 @@
+module Import
+  extend ActiveSupport::Concern
+
+  def import
+    if params[:file].nil?
+      flash[:error] = "No file was attached!"
+    else
+      begin
+        controller_name.classify.constantize.import(params[:file].read)
+        flash[:notice] = "Points were imported successfully!"
+      rescue ImportError => e
+        raise e
+        flash[:error] = e.message
+      end
+    end
+
+    redirect_to action: :index
+  end
+end

app/errors/import_error.rb

@@ -0,0 +1 @@
+class ImportError < StandardError; end

app/models/concerns/importable.rb

@@ -0,0 +1,13 @@
+module Importable
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def importer(importer_klass)
+      @importer_klass = importer_klass
+    end
+
+    def import(data)
+      @importer_klass.new(data).import
+    end
+  end
+end

config/routes.rb

@@ -1,4 +1,10 @@
 Rails.application.routes.draw do
+  concern :import do
+    collection do
+      post :import
+    end
+  end
+
   namespace :admin do
     resources :users
     resources :speakers
@@ -8,8 +14,8 @@
     root to: "users#index"
   end
 
-    delete '/admin/places' => 'places#delete'
-    delete '/admin/stories' => 'stories#delete'
+  delete '/admin/places' => 'places#delete'
+  delete '/admin/stories' => 'stories#delete'
 
   scope "(:locale)", locale: Regexp.union(I18n.available_locales.map(&:to_s)) do
     resources :places do