Refine the LitCalDecreesSource schema

[JohnRDOrazio]

Currently, the LitCalDecreesSource.json schema is very lax and generic. It tries to accomodate all possible scenarios by simply not requiring most properties.

It would be better to define precisely the shape of the various decrees based on their metadata->action property. Each type of action requires specific properties.

This should be quite similar to the NationalCalendar.json schema, where the shape of the items is defined precisely based on the metadata->action property:

LiturgicalCalendarAPI/jsondata/schemas/NationalCalendar.json

Lines 10 to 29 in b8b6ee0

	"oneOf": [
	{
	"$ref": "#/definitions/LitCalMoveFestivity"
	},
	{
	"$ref": "#/definitions/LitCalSetPropertyGrade"
	},
	{
	"$ref": "#/definitions/LitCalSetPropertyName"
	},
	{
	"$ref": "#/definitions/LitCalMakePatron"
	},
	{
	"$ref": "#/definitions/LitCalCreateNewFixed"
	},
	{
	"$ref": "#/definitions/LitCalCreateNewMobile"
	}
	]