Add regular schedules

Allows importing regular opening and closing times for a location
and/or service.

Valid values for the `weekday` field are:

- Integer or String between 1 and 7, where 1 means Monday.

- String of full weekday name, such as “Monday”

- String of abbreviated 3-letter weekday name, such as “Tue”

Valid values for the `opens_at` and `closes_at` fields are:

- String representing hour in 24-hour format, such as “09:00” and
“17:00”.

- String using “am” and “pm”, such as “10am” and “5pm”.

Also adds the ability to edit hours of operation for both locations and services via the admin interface.