make attachment upload WORK

lets see if we can make it GOOD, I think it already is FAST ^^

lib/api/v3/attachments/attachments_by_work_package_api.rb

@@ -40,6 +40,31 @@ module API
                                                 attachments.count,
                                                 self_path)
           end
+
+          post do
+            authorize(:edit_work_packages, context: @work_package.project)
+
+            metadata = params[:metadata]
+            file = params[:file]
+
+            # TODO: verify input (valid JSON + file given)
+
+            # FIXME: we should be using the representer to parse the metadata
+            parsed_metadata = JSON.parse(metadata)
+
+            uploaded_file = Rack::Multipart::UploadedFile.new file[:tempfile].path,
+                                                              file[:type],
+                                                              true
+            # I wish I could set the file name in a better way *sigh*
+            uploaded_file.instance_variable_set(:@original_filename, parsed_metadata['fileName'])
+            attachment = Attachment.new(file: uploaded_file,
+                                   container: @work_package,
+                                   description: parsed_metadata['description']['raw'],
+                                   author: current_user)
+            attachment.save!
+
+            ::API::V3::Attachments::AttachmentRepresenter.new(attachment)
+          end
         end
       end
     end