Pinned "faraday" dependency for "ridley" to 0.8.9

Prevent error:

    /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/faraday-0.9.0/lib/faraday.rb:99:in `method_missing': undefined method
    `register_middleware' for #<Faraday::Connection:0x000000035e5b48> (NoMethodError)

Related: RiotGames/ridley#239, RallySoftware-cookbooks/cookbook-development@a92d3b9