fastlane: Unable to access `build_trains` from Spaceship

New Issue Checklist

• Updated fastlane to the latest version
• I read the Contribution Guidelines
• I read docs.fastlane.tools
• I searched for existing GitHub issues

Issue Description

$ bundle exec fastlane spaceship
Logging into to iTunes Connect (***@***.com)...
Successfully logged in to iTunes Connect

Logging into the Developer Portal (***@***.com)...
Successfully logged in to the Developer Portal

---------------------------------------
| Welcome to the spaceship playground |
---------------------------------------

Enter docs to open up the documentation
Enter exit to exit the spaceship playground
Enter _ to access the return value of the last executed command

Just enter the commands and confirm with Enter
[1] pry(#<Spaceship::Playground>)> Spaceship::Tunes::Application.all.first.build_trains
Spaceship::Client::UnexpectedResponse: Temporary iTunes Connect error: <?xml version="1.0" encoding="UTF-8"?>
<String>There is no route for the path 'apps/MY_APP_ID_HERE/trains/'.</String>
from /Users/rax/.rvm/gems/ruby-2.2.3/gems/fastlane-2.64.1/spaceship/lib/spaceship/tunes/tunes_client.rb:799:in `rescue in build_trains'
[2] pry(#<Spaceship::Playground>)>

Note: In the error log, it shows actual app ID instead of MY_APP_ID_HERE.

It appears that the URL to get build_trains now includes platform in it, which looks like: apps/APP_ID/platform/[ios|appletvos]/trains.