Edition controller: openForEnrolment enum and patching

(This is for implementing cse2000-software-project/2019-2020-q4/cluster-7/cpmates/cpm2#130)

The idea would be to have an openForEnrolment enum. Currently, there is a boolean openForEnrolment but it is not used referenced anywhere else in LabraCORE. I suggest either making this boolean into enum or having a separate enum called openForEnrolmentStatus (if the boolean will be needed).

The types of the enum should be:

• OPEN
• OPEN_TO_PROGRAM
• CLOSED

This variable, whichever it ends up being, should also be in EditionPatchDTO.

DTOs required

Name: EditionPatchDTO

This DTO is a:

• Create
• Patch
• View

This DTO should also have all the other already existing fields. This is merely adding something in there, not creating a new Patch DTO.

The DTO has the following fields:

Type	Name	Comment
OpenToEnrolment(Status)	openToEnrolment(Status)	Status would be there if we keep around the boolean as well.