need to_s before blank? check in query param construction

[scootklein]

json_stream.rb:298

it's possible that params get passed in as Fixnum or Boolean types that won't respond to blank? when iterating and constructing the query string. adding a to_s will prevent exceptions.

def params
  flat = {}
  @options[:params].merge!(:track => @options[:filters]) unless @options[:filters].blank?
  @options[:params].each do |param, val|
    next if val.to_s.empty?
    val = val.join(",") if val.respond_to?(:join)
    flat[escape(param)] = escape(val)
  end
  flat
end