Import feature for following/blocking lists (addresses #62, #177, #201, #454)

db/migrate/20170330164118_add_attachment_data_to_imports.rb

@@ -0,0 +1,11 @@
+class AddAttachmentDataToImports < ActiveRecord::Migration
+  def self.up
+    change_table :imports do |t|
+      t.attachment :data
+    end
+  end
+
+  def self.down
+    remove_attachment :imports, :data
+  end
+end