NLP: Support weekly by hour patterns

[Aviad Pineles]

In the NLP module, It is currently not possible to parse a weekly recurrence that also has by hour specifications, e.g.

Every week on Sunday at 10, 12 and 17

I would expect it to serialize to RRULE:FREQ=WEEKLY;BYDAY=SU;BYHOUR=10,12,17

Also above pattern when converted to text omits the "by hour" specification (i.e. yields Every week on Sunday)