Remove faraday warning

When running the tests this warning message would appear:

    /Users/blake/.rvm/gems/ruby-2.0.0-p481-turbo/gems/faraday-0.9.0/lib/faraday/request/url_encoded.rb:12:
    warning: wrong element type Hash at 0 (expected array)
    /Users/blake/.rvm/gems/ruby-2.0.0-p481-turbo/gems/faraday-0.9.0/lib/faraday/request/url_encoded.rb:12:
    warning: ignoring wrong elements is deprecated, remove them
    explicitly
    /Users/blake/.rvm/gems/ruby-2.0.0-p481-turbo/gems/faraday-0.9.0/lib/faraday/request/url_encoded.rb:12:
    warning: this causes ArgumentError in the next release

I tracked it down to the splat operator in the create_user method
arguments. My understanding is that if you want to pass in a hash as an
argument you shouldn't use the splat operator.