Define message-summary dict keys as constants

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
diff --git a/docs/release-notes.rst b/docs/release-notes.rst
index b28a846..8a5001f 100644
--- a/docs/release-notes.rst
+++ b/docs/release-notes.rst
@@ -10,13 +10,12 @@
 The format is based on `Keep a Changelog <http://keepachangelog.com/>`__
 and this project adheres to `Semantic Versioning <http://semver.org/>`__.
 
-.. contents::
-   :depth: 3
-   :local:
 
-[1.0.4] - 2020-05-05
+[1.1.0] - 2020-05-06
 --------------------
 * Use RMR timeout on receive to avoid 100% CPU usage (`RIC-354 <https://jira.o-ran-sc.org/browse/RIC-354>`_)
+* Publish message-summary dict keys as constants to avoid hardcoding strings
+* Add wrapper and test for RMR method rmr_set_vlevel(int)
 
 
 [1.0.3] - 2020-04-29
@@ -70,7 +69,6 @@
 * Switch to SI95 for rmr
 
 
-
 [0.5.0] - 3/18/2020
 -------------------
 
@@ -110,6 +108,7 @@
   and call stop() when they want.
 * Raises tox coverage minimum to 70 from 50 (currently at 86)
 
+
 [0.2.0] - 3/3/2020
 ------------------
 
@@ -129,6 +128,7 @@
   page looks nicer
 * Removes a bad release file (will be added back in subseq. commit)
 
+
 [0.1.0] - 2/27/2020
 -------------------