Remove deprecated API elements from protocol framework

The use of these concepts has been deprecated in version 0.4.0, which
was released. The only in-tree user was netconf, which was refactored to
not to rely on these concepts, so bump the version to 0.5.0 and purge
the  code.

Change-Id: Ibf2195b51bf12ea99b8b21f3da322d666b103b5e
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "Remove deprecated API elements from protocol framework"