REFACTORED: The URI parameter is optional now (the Java API and the parser will check if this is valid for the specific section).

Signed-off-by: Michael Grammling <m.grammling@external.telekom.de>
REFACTORED: thing-description -> thing-descriptions
ADDED: bindingId for the root node so that all other UIDs can be replaced by IDs only.
CHANGED: description is optional now.

Signed-off-by: Michael Grammling <m.grammling@external.telekom.de>
CHANGED: description is optional now.

Signed-off-by: Michael Grammling <m.grammling@external.telekom.de>