Joes-giant-toolbox

* Added function **joes_giant_toolbox.text.longest_common_substring()**

* Added function **joes_giant_toolbox.google_cloud.gcloud_vm_deletes_itself()**

* Added function **joes_giant_toolbox.web.parse_mime_email_parts()**

* Added function **joes_giant_toolbox.web.require_api_key()**

* Small change to documentation code example in create_parallel_google_cloud_run_job_template()

* Added function **joes_giant_toolbox.google_cloud.create_parallel_google_cloud_run_job_template()**

* Added function **joes_giant_toolbox.google_cloud.gcloud_vm_deletes_itself()**

* Improved quality of **joes_giant_toolbox.text.RegexRulesClassifier** code (perfect pylint score)

* Method **remove_non_letters()** in **joes_giant_toolbox.text.StringCleaner()** no longer removes whitespace

* Improved the behaviour of **joes_giant_toolbox.text.RegexRulesClassifier** for the case where no rules match and ties_handling=="all"