Sinatra app_path, similar to uri/url/to but with optional params

app_path.rb

def app_path(path, params={})
  if params.size == 0
    uri(path)
  else
    query_string = ""
    params.each_pair do |key, value|
      query_string += key.to_s + '=' + escape(value.to_s)
    end
    uri(path) + '?' + query_string
  end
end