Refactor code to eliminate hardcoded strings like "message state".
Add wrapper method and test for method rmr_set_vlevel.
Unpin xappframepy version in Ping/Pong Dockerfiles.
Use constants for message-state values instead of integers.
Drop all mentions of NNG.
Bump version to 1.1.0.
Signed-off-by: Lott, Christopher (cl778h) <cl778h@att.com>
Change-Id: I27c0bcb4ae6d6a85b518510fd1a4c651d3445313