REST API changes for user settable server description

This patches adds changes to the Nova REST API to allow
users to create a server with a description, rebuild
a server with a description, update the description,
and get the description in the server details.

Note: Future commits will be done to support the server
description in python-novaclient and openstack-client.

APIImpact

Implements blueprint: user-settable-server-description

Change-Id: I74b1a340c5ab98fdea2186e87dd13f42ce7c7661

nova/api/openstack/api_version_request.py

@@ -60,6 +60,7 @@ REST_API_VERSION_HISTORY = """REST API Version History:
     * 2.16 - Exposes host_status for servers/detail and servers/{server_id}
     * 2.17 - Add trigger_crash_dump to server actions
     * 2.18 - Makes project_id optional in v2.1
+    * 2.19 - Allow user to set and get the server description
 """
 
 # The minimum and maximum versions of the API supported
@@ -68,7 +69,7 @@ REST_API_VERSION_HISTORY = """REST API Version History:
 # Note(cyeoh): This only applies for the v2.1 API once microversions
 # support is fully merged. It does not affect the V2 API.
 _MIN_API_VERSION = "2.1"
-_MAX_API_VERSION = "2.18"
+_MAX_API_VERSION = "2.19"
 DEFAULT_API_VERSION = _MIN_API_VERSION