Support timeago in jinja2 templates

[neponn]

I'm wondering whether it is possible to introduce support for the timeago library (https://pypi.org/project/timeago/) or something like it, to make it easy to provide human readable duration statements when using templates in the GUI.

For example, timeago can be as simple as:

>>> import datetime, timeago
>>> then = datetime.datetime.now()
>>> print(timeago.format(then))
15 seconds ago

It would be very nice if it was possible in the GUI to use jinja templates like:

{{ states('sensor.outside_temperature') }}°, {{ timeago.format(states.sensor.outside_temperature.last_updated) }}

Which would yield:

19.7°, 15 seconds ago

This would save a heap of manual jinja manipulation to approximate a similar result.