Remove xhr and xml_http_request due to rails 5 deprecation warning

[Shuiei]

DEPRECATION WARNING: xhrandxml_http_requestare deprecated and will be removed in Rails 5.1. Switch to e.g.post :create, params: { comment: { body: 'Honey bunny' } }, xhr: true.

[rails-bot]

Thanks for the pull request, and welcome! The Rails team is excited to review your changes, and you should hear from @rafaelfranca (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

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[Shuiei]

Do I need to make a condition to remove or not xhr and xml_http_request which depend on the rails version ?

[rafaelfranca]

Yes, we need a conditional because this gem needs to work in Rails 5.0

[Shuiei]

Okay. I'm on it.

[Shuiei]

@rafaelfranca PR updated as requested