Add: Ability to pass `Map` into RestApplication

This allows a developer to pass in an already created
`Map` for use in URL routing in addition to being able
to pass in an iterable of service objects.

Signed-off-by: Kevin Conway <kevinjacobconway@gmail.com>
Add: Additional details to README

Signed-off-by: Kevin Conway <kevinjacobconway@gmail.com>