Allow SchemaComposition s to have titles

[captnCC]

Hi,
as SchemaCompositions should comply to the SchemaContract and can be used in the same way, they should be able to have titles.
For now, I can add them to the components/schemas list, but they can't have a title and will be displayed by their objectId.
It's mostly a cosmetic thing, but would be a nice to have for overall consistency.

[matthew-inamdar]

I'll look at adding this in the next release.