Stride#configuration should return a default object instead of nil

[mbobin]

Hello!

I was trying to use it without calling Stride#configure and stumbled onto this issue.

require 'stride'
client = Stride::Client.new(:cloud_id, :conversation_id, :access_token)

client.send_message({})
NoMethodError: undefined method `api_base_url' for nil:NilClass
from /Users/marius/.gem/ruby/2.4.4/gems/stride-0.1.1/lib/stride/message.rb:32:in `uri'

Should I draft a pull request to change lib/stride.rb ?

module Stride
  class << self
    attr_writer :configuration
   
    def configuration
      @configuration ||= Configuration.new
    end
  end

  def self.configure
    yield(configuration)
  end
end

Thank you!