Changes to better integrate with core ContentBlocks

[isaacniebeling]

• Changed field to selectinput (it can be used for more than just classes). Will require updating field type for existing fields from classselectinput to select input.
• Changed order from value=Display to Display=value to match core CB. Will require flipping order in existing fields.
• Changed delimiter from comma to newline to match core CB. Will require replacing commas with newlines in existing fields.