Fix download on electron

packages/rocketchat-message-attachments/client/messageAttachment.coffee

@@ -12,6 +12,8 @@ Template.messageAttachment.helpers
 
 		if Meteor.settings.public.sandstorm or url.match /^(https?:)?\/\//i
 			return url
+		else if navigator.userAgent.indexOf('Electron') > -1
+			return __meteor_runtime_config__.ROOT_URL_PATH_PREFIX + url
 		else
 			return Meteor.absoluteUrl().replace(/\/$/, '') + __meteor_runtime_config__.ROOT_URL_PATH_PREFIX + url
 

packages/rocketchat-ui-flextab/flex-tab/tabs/uploadedFilesList.coffee

@@ -40,6 +40,8 @@ Template.uploadedFilesList.helpers
 
 		if Meteor.settings.public.sandstorm or url.match /^(https?:)?\/\//i
 			return url
+		else if navigator.userAgent.indexOf('Electron') > -1
+			return __meteor_runtime_config__.ROOT_URL_PATH_PREFIX + url
 		else
 			return Meteor.absoluteUrl().replace(/\/$/, '') + __meteor_runtime_config__.ROOT_URL_PATH_PREFIX + url