Improve date normalization and tests for Harvard collections

[jacobthill]

As the DLME data manager I need to improve date normalization for some collections. Both Harvard collections have some date values that are not mapped due to inconsistency in the values. The date normalization macros need to be revised and better tests need to be written.

Requirements:

• Investigate date normalization macros and results to see if improvement is possible.
• Improve, if possible, and document any limitations to date normalization in https://drive.google.com/drive/folders/1rak3-GXk9N0CZig-daDeHidAZrfASeV5