Extracted ThingTypeRegistry from ThingRegistry

Signed-off-by: Oliver Libutzki <o.libutzki@external.telekom.de>
Added some Javadoc

Signed-off-by: Oliver Libutzki <o.libutzki@external.telekom.de>
Merge branch 'thing-concept-contribution' of https://github.com/qivicon/smarthome into thing-concept-contribution

Signed-off-by: Oliver Libutzki <o.libutzki@external.telekom.de>