Cdcs

- PID PATH/XPATH operations updated to reflect xpath->path renaming in CDCS database version 3.6.
- Code cleanup that should have no effect except that Python < 3.7 no longer supported.
- The ability to toggle the auto_set_pid added and integrated into upload_record() and update_record() methods.
- A retry504 option added to RestClient.requests to retry a REST call if the connection is poor.
- Bug fixes related to CDCS version 3 databases.
- Default column titles added for when get_templates and get_template_managers finds no matches to help avoid bugs.

Updated tests. Minor upkeep to fix depreciation warnings.

Bug fixes related to guessing the CDCS version when not given and removing generator exit warning messages.

Code updated to support CDCS versions 3.x.x.

Automatic interpretation of datetime fields into Python objects added to get and query methods for records and templates. Progress bar added to query. Template operations extended to include administration capabilities such uploading, updating, disabling and restoring. Operations for uploading, modifying and deleting XSLT files and PID XPATHs added.

Package requirements cleaned up. An inadvertent unused package import removed.