v2.9.0

• Remove deprecated autorequire from gemspec.
  #123
• Rescue from Yadis::XRI::XRIHTTPError on discovery.
  #106
• Avoid SSRF for claimed_id request.
  #121
• Updated documentation.
  #115, #116, #117, #118
• Reduce warnings output in test runs.
  #119
• Drop deprecated option from gemspec.
  #120
• Remove circular require.
  #113
• Updated Travis CI config with Ruby 2.6
  #114
• Simplify Bundler require; remove need for extra :require.
  #112