URI validation for the ConfigDescriptions

Also-by: Dennis Nobel <d.nobel@external.telekom.de>
Also-by: Michael Grammling <m.grammling@external.telekom.de>
Signed-off-by: Alex Tugarev <telekom@tugarev.de>
Merge pull request #75 from qivicon/uri-fix-contribution

URI validation for the ConfigDescriptions