Cities/work calendars should contain default journey information

[jaragunde]

When a organization-wide change to work journey happens, it's painful to apply it to every active user in the system.

The idea is to allow cities/work calendars to contain this information about work journeys: start, end dates and daily journey. Users will be applied this configuration as long as they are assigned to that city/work calendar, and in case they don't have their own journey values overwriting it.

Example:

• City has journey of 8 hours per day from 2018-01-01 to 2018-12-31.
• User is assigned to City from 2018-02-01 to 2019-12-31.
• User has journey of 4 hours from 2018-06-01 to 2018-06-30.
• Results:
  • On 2018-01-01, user's journey is 0 (not yet assigned to the city).
  • On 2018-02-01, user's journey is 8.
  • On 2018-06-01, user's journey is 4 (user has its own journey value overwriting the city's).
  • On 2018-07-01, user's journey is back to 8.
  • On 2019-01-01, user's journey is 0 (city has no journey value for that date).

[jaragunde]

Maybe we should simplify this feature and allow only one default journey value per year assigned to a city/work calendar. It would fit well with the implementation of #359, and it's likely that we don't need such a fine-grain configuration to this, we still have user journeys for that.

Following the previous example, results would be exactly the same with a configuration for City like this: 2018 -> 8 hours, no configuration for 2019.