Bugfix rtm

## example
```ruby
irb(main):003:0> params = {token: "aaa", "channel" => "#general"}
=> {:token=>"aaa", "channel"=>"#general"}

irb(main):004:0> URI.encode_www_form([params])
=> "%7B%3Atoken%3D%3E%22aaa%22%2C+%22channel%22%3D%3E%22%23general%22%7D"

irb(main):005:0> URI.encode_www_form(params)
=> "token=aaa&channel=%23general"
```