Support for persisting Ngrok process data

• Initial commit after forking and renaming the ngrok-tunnel gem
• Support for persisting Ngrok process data for possible re-use when restarting the server
• Added github_changelog_generator to the gemspec #14 (texpert)
• Described gem's usage in Rails, move the description from examples folder into README.md #13 (texpert)
• Fix Codeclimate rubocop channel to beta to enable latest 1-24-1 #11 (texpert)
• Add codeclimate fixme and rubocop plugins #10 (texpert)
• Decompose fetch_urls for maintainability #9 (texpert)
• Refactor ngrok_running? to re-use ngrok_process_status_lines instead of a shell process #8 (texpert)
• Raise if Ngrok with the pid from persistence file is running on other port #7 (texpert)
• Refactor DRYing ngrok_exec_params method #6 (texpert)
• Remove redundant methods and introduce :params read accessor #5 (texpert)
• Don't forget to close the log file and don't use returns in a block #4 (texpert)
• Fix CI setup-ruby action to use Ruby version from strategy matrix #3 (texpert)
• Fix CodeClimate issue Class Wrapper has 22 methods (exceeds 20 allowed) #2 (texpert)
• Fix the specs to avoid trying to run real Ngrok when testing using fixture log files #1 (texpert)