Open next semester

[Daníel Sigurgeirsson]

There should be an API for opening the next semester. It could simply be:

/api/v1/semesters -> PUT

What happens in this method would be the following:

• validation - we shouldn't be able to open the next semester unless all course instances on the current semester have been closed.
• create a new semester object - note that this is probably a semester sometime in the future, perhaps 2-3 years ahead. We might want to allow the data for this semester (the main name, the English name, the semester ID) to be passed as parameters to the API
• set the current, prev and next semester properties
• post an event on our Message queue, notifying others that this happened.

Note: SchoolServiceProvider.MoveToNextSemester() already has an empty function, which needs to be implemented.