Update image tagging to include a datetime

[JeremyGibson]

Currently image.generate_tag produces a tag that only includes the commit hash. This is helpful, but often when quickly debugging an issue with a deployment it is helpful to have a more information dense tag specifically having the datetime included.

AC:

• add a datetime to the tag datetime.now(pytz.timezone("America/New_York")).strftime("%Y-%m-%d-%H.%M.%S")
• make this optional?