Add date range support to access control rules

[tw4l]

Description

Fixes #703

This PR adds date range support to ACL rules that uses the existing embargo syntax.

Access can be controlled by specifying before or after a particular timestamp, e.g.

org,iana)/ - {"access": "allow", "url": "http://www.iana.org/", "before": "20140126"}

Time intervals can also be used via newer and older, e.g.:

org,iana)/ - {"access": "allow", "url": "http://www.iana.org/", "newer": {"years": 1, "months": 6}}

Documentation has also been added.

Motivation and Context

This will allow users to block/allow a subset of captures from a URL based on date, e.g. in the case where ownership of a URL changed at some point.

Types of changes

• Replay fix (fixes a replay specific issue)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added or updated tests to cover my changes.
• All new and existing tests passed.